| Project/Area Number |
24651011
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| Research Category |
Grant-in-Aid for Challenging Exploratory Research
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| Allocation Type | Single-year Grants |
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| Research Field |
Environmental dynamic analysis
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| Research Institution | Kyushu University |
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Principal Investigator |
KITA Itsuro 九州大学, 比較社会文化研究科(研究院), 教授 (10143075)
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| Co-Investigator(Renkei-kenkyūsha) |
SATO Tokiyuki 秋田大学, 工学資源学部, 教授 (60241668)
OHNO Masao 九州大学, 大学院比較社会文化研究院, 准教授 (00251413)
KUWAHARA Yoshihiro 九州大学, 大学院比較社会文化研究院, 准教授 (90281196)
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| Project Period (FY) |
2012-04-01 – 2014-03-31
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| Project Status |
Completed (Fiscal Year 2013)
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| Budget Amount *help |
¥3,770,000 (Direct Cost: ¥2,900,000、Indirect Cost: ¥870,000)
Fiscal Year 2013: ¥1,430,000 (Direct Cost: ¥1,100,000、Indirect Cost: ¥330,000)
Fiscal Year 2012: ¥2,340,000 (Direct Cost: ¥1,800,000、Indirect Cost: ¥540,000)
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| Keywords | マーキュリー / ミレニアム解析 / 氷床拡大縮小 / 氷床の出現・発達期 / ナンノプランクトン / 北大西洋 / 透光帯水塊構造 / ＩＯＤＰ / マ－キュリー / 水銀 / 海洋底堆積物 / 有機物 / 窒素同位体比 / 炭素同位体比 / 氷床拡大期 / 千年周期 |
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| Research Abstract |
It was clarified that mercury contents in the North Atlantic sediments over the last 1,000,000 years and during a period between 2500 ka and 2550 ka changed with distinct periods of 100,000 and 41,000 years, and 3000 and 5000 years, respectively. The sediment Hg content increased during glacial periods with the increase of ice-rafted debris (IRD), correlating positively with total organic carbon content and inversely with its carbon isotopic ratio and the absolute abundance of surface-dwelling nannoplankton species. These observations suggest that Hg- and IRD-bearing icebergs flowed out to this sea area melted during glacial periods and the increased Hg of photic water is incorporated into the organic matter produced by deep-dwelling phytoplankton in the lower photic zone. Sediment Hg content can be used as a new chemical indicator of enlargement and reduction of ice floes in the northern hemisphere in both orbital and millennium scales
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