Grant-in-Aid for international Scientific Research
|Allocation Type||Single-year Grants |
|Research Institution||National Institute of Polar Research |
WATANABE Okutsugu National Institute of Polar Research (N. I. P. R) -> 国立極地研究所, 研究系, 教授 (60111861)
WOLD B Norwegian Water Resources and Energy Administration, 主任
THOMSEN H. H The Geological Survey of Greenland, Denmark Government, 研究員
KAWAMURA Kimitaka Faculty of Science, Tokyo Metropolitan University, 理学部, 助教授 (70201449)
HAGEN J. O Norwigian Polar Research Institute, 研究員
NAKAZAWA Takakiyo Faculty of Science, Tohoku University, 理学部, 助教授 (30108451)
AOKI Shuji National Institute of Polar Research (N. I. P. R), 研究系, 助手 (00183129)
SATOW Kazuhide National Nagaoka College of Technology, 助教授 (80113398)
IZUMI Kaoru Research Institute for Harzards in Snow Area, Niigata Univ., 助教授 (50114997)
KAWADA Kunio Faculty of Science, Toyama University, 理学部, 助手 (20019003)
KAMIYAMA Koukichi Faculty of Science, Kyoto University, 理学部付属地球物理学研究施設, 助手 (70135507)
NARITA Hideki Institute of Low Temperature Science Hokkaido University, 研究所, 講師 (20001662)
SHIJI Hitoshi Faculty of Science, Toyama University, 理学部, 助教授 (50201562)
NISHIO Fumihiko Hokkaido University of Education, Kushioro Campus, 釧路分校・教育学部, 教授 (40044789)
FUJII Yoshiyuki National Institute of Polar Research (N. I. P. R), 研究系, 助教授 (20125214)
CLAUSEN H University of Cophenhagen, Geophysical Institute
|Project Period (FY)
1989 – 1990
|Keywords||Arctic Region / Greenland Ice Sheet / Ice Core Analyses / Climatic Change / Environmental Change / Acid Rain / Little Ice Age / Volcanic Event Signal|
Summary of Greenland Ice Core Investigations
Ice cores from polar glaciers and ice sheets provide the means to study the climatic and environmental changes in the past by conducting physical and chemical stratigraphic anlyses on the cores. A team member of the Japanese Arctic Research Expedition (JAGE) successfully obtained one 101m-long and one 205m-long ice cores at Site J (65^ﾟ 51.9' N, 46^ﾟ 15.9' w), Greenland during the field activities in May-July, 1989. The field observations on the cores included visual stratigraphy (continuous) and ECM measurements (continuous), and pH and EC examinations (discrete). Cores after processing in the field were transported to Japan for detailed, multi-parameter laboratory investigations. The results hitherto obtained on cores are summarized as follows.
Chronology : Accumulation rate at Site J was studied by conducting measurements on visual stratigraphy, delta^<18>O, tritium and ^<210>Pb analyses. ECM profile obtained shows well-defined peaks at dep
ths of 86.9 and 102.8m, which are associated with the known volcanic events in 1815 (Tambora) and 1783 (Laki) respectively. These findings suggest that an average accumulation rate at Site J for the period from 1783 to 1988 AD is 0.39m/a and the age of ice at the bottom of the 205m-long core is 435 a B. P.
Temperature : Melt feature percentages (MFP) of the cores were analysed to extract information on the near surface temperature record in the past. The depth variations of MFP profile generally correlate well with delta^<18>O changes. Two minima observed in MFP profile at depths of 78 and 150m, corresponding to around 1840 and 1690 AD respectively, may reflect an occurrence of a colder period known as Little Ice Age.
Chemistry : The major ion concentrations such as SO_4, NO_3, Na, Cl and K were measured on selected samples. The anthropogenic SO_4 and NO_3 inputs to Greenland are clearly demonstrated after the industrial revolution and rapidly increased in the 20-th century as also shown in the profile. Organic chemistry analysis has been made on various species including particulate organic carbon, hydrocarbon and carboxylic acid. A siginificant increase in anthropogenic hydrocarbon concentration (unresolved complex mixture) is observed in the 20-th century.
An international workshop was held to discuss and cross-correlate the various study results, and summarize the present status of knowledge for future research directions. An emphasis was made on the necessity to conduct shallow-core network analyses for a betterunderstanding of the environmental characteristics in Arctic region. Less