全学体験ゼミナール

こんにちは、M2の平林です。

2/21(金)に東大駒場生対象の全学体験ゼミナールが開催されました。

理系の学生が大半でしたが、なんと文系の学生の方も参加してくださいました！

横山研では、放射性炭素年代測定についての説明をした後、AMS見学や、

放射性炭素年代測定の前処理準備に行うFeの秤量やプレスを体験していただきました。

参加してくださった学生の皆さん、

将来横山研のメンバーになることを期待しています(笑)

AMS棟にて、横山先生が放射性炭素年代測定について説明中。

宮入さんと行くAMS見学ツアー！

Fe秤量とプレスの仕方の説明中

参加してくださり、ありがとうございました！

新着論文紹介 This Week’s New Paper (2014/2/24) AGU, etc…

☆Global Biogeochemical Cycles☆

1.  The role of soil processes in δ¹⁸O terrestrial climate proxies

Lisa C. Kanner, Nikolaus H. Buenning, Lowell D. Stott, Axel Timmermann, David Noone

DOI: 10.1002/2013GB004742

Keywords:

oxygen isotopes; tree cellulose; evaporation; soil water isotopes

☆Geophysical Research Letters☆

2.  Impact of the Atlantic Meridional Overturning Circulation on Ocean Heat Storage and Transient Climate Change

Yavor Kostov, Kyle C. Armour, John Marshall

DOI: 10.1002/2013GL058998

Keywords:

climate change; CMIP5; inter-model spread; climate sensitivity; ocean heat uptake; AMOC

3.  Comparison of Surface Albedo Feedback in Climate Models and Observations

A. Crook, P. M. Forster

DOI: 10.1002/2014GL059280

Keywords:

surface albedo feedback; climate change

☆Journal of Geophysical Research: Oceans☆

4.  On the ability of global sea level reconstructions to determine trends and variability

F. M. Calafat, D. P. Chambers, M. N. Tsimplis

DOI: 10.1002/2013JC009298

Keywords:

Sea level; Reconstruction; Variability; Tide gauge; Trend; Model

5.  Circulation in the southern Great Barrier Reef studied through an integration of multiple remote sensing and in situ measurements

Yadan Mao, John L. Luick

DOI: 10.1002/2013JC009397

Keywords:

Capricorn Eddy; Upwelling; Stratification; Tidal currents; Great Barrier Reef

Journal Review 19 – 25 Feb 2014 (Nature, Science, Nature Geoscience, Nature Communications)

NATURE

1. China plunges into ocean research

Nature 506, 276 (20 February 2014) doi: 10.1038/506276a

China has embarked on a five-year research project called the Western Pacific Ocean System (WPOS) and it will deploy five ships, a remotely operated submersible and an array of sub-surface moorings off the eastern coasts of Philippines and Indonesia to investigate the western Pacific warm pool and the Kuroshio current.

2. Conservation: Nicaragua Canal could wreak environmental ruin

Axel Meyer & Jorge A. Huete-Perez

Nature 506, 287-289 (20 February 2014) doi: 10.1038/506287a

A planned 300-kilometre waterway joining the Pacific and Atlantic oceans could result in destruction of around 400 000 hectares of rainforests and wetlands and subsequently endanger ecosystems. Independent environmental assessment should be carried out before any construction is to take place.

3. Prodigious degassing of a billion years of accumulated radiogenic helium at Yellowstone

J. B. Lowenstern, W. C. Evans, D. Bergfeld & A. G. Hunt

Nature 506, 355-358 (20 February 2014) doi: 10.1038/nature12992

The authors combine gas emission rates with chemistry and isotopic analyses to show that crustal helium-4 emission rates from Yellowstone exceed crustal generation rates. This implies that helium has accumulated in Archaean cratonic rocks beneath Yellowstone only to be liberated over the past two million years by intense crustal metamorphism induced by the Yellowstone hotspot. 

SCIENCE

4. Atlantic current can shut down for centuries, disrupting climate

Richard A. Kerr

Vol. 343 no. 6173 p. 831 doi:10.1126/science.343.6173.831

Using an epibenthic foraminiferal δ¹³C record, researchers showed that North Atlantic Deep Water influence was strong at the onset of the last interglacial period and then interrupted by several prominent, centennial-scale reductions. These occurred during periods of increased ice rafting and southward expansions of polar water influence, suggesting a buoyancy threshold for convective instability was triggered by freshwater and circum-Arctic cryosphere changes. The vulnerability of the Atlantic circulation may have a huge impact on future climate.

5. From past to future warming

Gabi Hegerl & Peter Stott

Vol. 343 no. 6173 pp. 844-845 doi: 10.1126/science.1249368

According to the IPCC Fifth Assessment Report, anthropogenic influence on Earth climate is ‘extremely likely’ to cause more than half of the observed increase in global average temperature from 1951 to 2010. However, the uncertainty in the estimated contribution of greenhouse gases to the observed global-mean warming is still large. Data gaps and other variables may mask the reality and cause inaccuracies in models.

NATURE GEOSCIENCE

6. Saharan lake

Amy Whitchurch

Nature Geoscience 7, 82 (2014) doi: 10.1038/ngeo2089

Beryllium-10 isotope dating was used to date palaeolake shoreline deposits preserved in Sudan, eastern Sahara to about 109 000 years. The lake probably formed during the last interglacial period and was broadly similar in surface area to today’s largest freshwater lakes.

7. Extensive liquid meltwater storage in firn within the Greenland ice sheet

Richard R. Forster, Jason E. Box, Michiel R. van den Broeke, Clément Miège, Evan W. Burgess, Jan H. van Angelen, Jan T. M. Lenaerts, Lora S. Koenig, John Paden, Cameron Lewis, S. Prasad Gogineni, Carl Leuschen & Joseph R. McConnell

Nature Geoscience 7, 95-98 (2014) doi: 10.1038/ngeo2043

Radar and ice-core observations provide direct evidence of a perennial aquifer in the firn layer in southern Greenland that represents a potentially significant contribution to the Greenland mass budget. A regional climate model was used to estimate the aquifer area at about 70 000km² and the depth to the top of the water table as 5-50m.

8. Palaeoclimate: Lags within the Younger Dryas

Ana Moreno

Nature Geoscience 7, 87-88 (2014) doi: 10.1038/ngeo2072

A slowing Atlantic overturning circulation during the last deglacial warming caused abrupt cooling in the Northern Hemisphere. Rach et al. used a well-dated, annually resolved sediment core from Lake Meerfelder Maar in western Germany and measured the hydrogen isotopes of aquatic and terrestrial lipid biomarkers. Hydrological change in Europe was found to lag behind the temperature drop by almost 200 years.

NATURE COMMUNICATIONS

9. Greenhouse conditions induce mineralogical changes and dolomite accumulation in coralline algae on tropical reefs

Guillermo Diaz-Pulido, Merinda C. Nash, Kenneth R. N. Anthony, Dorothea Bender, Bradley N. Opdyke, Catalina Reynes-Nivia & Ulrike Troitzsch

Nature Communications 5, Article number: 3310 doi: 10.1038/ncomms4310

Due to the presence of multiple carbonate minerals with different solubilities in seawater, the algal mineralogical responses to changes in carbonate chemistry are poorly understood. The researchers found an increase in dolomite concentration in living crustose coralline algae under greenhouse conditions.

10. Discovery of a novel methanogen prevalent in thawing permafrost

Rhiannon Mondav, Ben J. Woodcroft, Eun-Hae Kim, Carmody K. McCalley, Suzanne B. Hodgkins, Patrick M. Crill, Jeffrey Chanton, Gregory B. Hurst, Nathan C. VerBerkmoes, Scott R. Saleska, Philip Hugenholtz, Virginia I. Rich & Gene W. Tyson

Nature Communications 5, Article number: 3212 doi: 10.1038/ncomms4212

Thawing permafrost promotes microbial degradation of cryo-sequestered and new carbon leading to the biogenic production of methane, creating a positive feedback to climate change. Microbial community composition along a permafrost thaw gradient in northern Sweden was looked at and a single archaeal phylotype Methanoflorens stordalenmirensis dominated partially thawed sites. Metagenomic sequencing suggests that this lineage is both prevalent and a major contributor to global methane production.

新着論文（27 - 23 Feb 2014, Elsevier）

○Earth and Planetary Science Letters

1. Prolonged monsoon droughts and links to Indo-Pacific warm pool: A Holocene record from Lonar Lake, central India

Sushma Prasad , A. Anoop , N. Riedel , S. Sarkar , P. Menzel , N. Basavaiah , R. Krishnan , D. Fuller , B. Plessen , B. Gaye , U. Röhl , H. Wilkes , D. Sachse , R. Sawant , M.G. Wiesner , M. Stebich

インド中央部のロナール湖（Lonar Lake）から得られた堆積物コアを用いて過去10kaの環境変動を復元。4.3-3.9ka、2.0-0.6kaに大きな干ばつがあった可能性が示唆。西赤道太平洋暖水域の温暖化とハドレー循環への影響が原因？また古代人の移動との関係性も議論。

2. Biogeography in 231Pa/230Th ratios and a balanced 231Pa budget for the Pacific Ocean

Christopher T. Hayes , Robert F. Anderson , Martin Q. Fleisher , Sascha Serno , Gisela Winckler , Rainer Gersonde

太平洋全域のコアトップの²³¹Pa/²³⁰Th比（生物生産や海洋深層循環の指標になる）を報告。東赤道太平洋や北太平洋では生物源オパールフラックスと良い相関が見られ、生物生産が支配的であるが、南太平洋では熱水活動による影響があり複雑化している。

○Geochimica et Cosmochimica Acta

1. Li/Mg Systematics in Scleractinian Corals: Calibration of the Thermometer

Paolo Montagna , Malcolm McCulloch , Eric Douville , Matthias López Correa , Julie Trotter , Riccardo Rodolfo-Metalpa , Delphine Dissard , Christine Ferrier-Pagès , Norbert Frank , André Freiwald , Steve Goldstein , Claudio Mazzoli , Stephanie Reynaud , Andres Rüggeberg , Simone Russo , Marco Taviani

褐虫藻を有する・有さない様々な種のサンゴ（ハマサンゴ・ミドリイシ・深海サンゴetc）の骨格のLi/Mgが良い温度指標となることを報告。温度との間に指数関数的な関係性があり、石灰化プロセスにも大きな影響を受けない。温度の復元精度は「0.9℃」ほどと、Sr/Caと同程度か、より良いかもしれない。

2. Characterizing oxygen isotope variability and host water relation of modern and subfossil aquatic mosses

Jiayun Zhu , Andreas Lücke , Holger Wissel , Christoph Mayr , Christian Ohlendorf , Bernd Zolitschka

パタゴニアから得られた水コケ（aquatic mosses）のセルロースのδ¹⁸Oやコケ由来の有機物のδ¹⁸Oが水のδ¹⁸Oを反映していることを示唆。

○Marine Geology

1. The Messinian Salinity Crisis: Past and future of a great challenge for marine sciences

Marco Roveri , Rachel Flecker , Wout Krijgsman , Johanna Lofi , Stefano Lugli , Vinicio Manzi , Francisco J. Sierro , Adele Bertini , Angelo Camerlenghi , Gert De Lange , Rob Govers , Frits J. Hilgen , Christian Hübscher , Paul Th. Meijer , Marius Stoica

○Global and Planetary Change

1. Tibet forcing Quaternary stepwise enhancement of westerly jet and central Asian aridification: carbonate isotope records from deep drilling in the Qaidam salt playa, NE Tibet

Wenxia Han , Xiaomin Fang , Chengcheng Ye , Xiaohua Teng , Tao Zhang

○Palaeogeography, Palaeoclimatology, Palaeoecology

1. A New Model for the Kellwasser Anoxia Events (Late Devonian): Shallow Water Anoxia in an Open Oceanic Setting in the Central Asian Orogenic Belt

Sarah K. Carmichael , Johnny A. Waters , Thomas J. Suttner , Erika Kido , Aubry A. DeReuil

2. Characterizing the middle Miocene Mi-events in the Eastern North Atlantic realm: a first high-resolution marine palynological record from the Porcupine Basin

Willemijn Quaijtaal , Timme H. Donders , Davide Persico , Stephen Louwye

3. A glimpse of the Quaternary monsoon history from India and adjoining seas

Rajeev Saraswat , Rajiv Nigam , Thierry Correge

モンスーンの始まった時期や最近の変動などのごく簡単なレビュー。

○Quaternary Science Reviews

1. Fish otolith geochemistry, environmental conditions and human occupation at Lake Mungo, Australia

Kelsie Long , Nicola Stern , Ian S. Williams , Les Kinsley , Rachel Wood , Katarina Sporcic , Tegan Smith , Stewart Fallon , Harri Kokkonen , Ian Moffat , Rainer Grün

オーストラリア南東部のウィランドラ湖群地域（世界遺産）で得られた19.4kaの化石耳石のSr/Ca・Ba/Ca・δ¹⁸O分析から、魚の回遊や、湖の環境変動を推定。魚が死ぬ前に湖の蒸発が非常に盛んになったこと（高塩分化）、それによって古代アボリジニによる魚の捕獲が容易になったことなどを示唆（easy prey hypothesis）。

2. An early advance of glaciers on Mount Akdağ, SW Turkey, before the global Last Glacial Maximum; insights from cosmogenic nuclides and glacier modeling

Mehmet Akif Sarıkaya , Attila Çiner , Himmet Haybat , Marek Zreda

○Quaternary Geochronology

1. Reliability of equivalent-dose determination and age-models in the OSL dating of historical and modern palaeoflood sediments

A. Medialdea , K.J. Thomsen , A.S. Murray , G. Benito

2. The efficiency of charcoal decontamination for radiocarbon dating by three pre-treatments – ABOX, ABA and hypy

Michael I. Bird , Vladimir Levchenko , Philippa L. Ascough , Will Meredith , Christopher M. Wurster , Alan Williams , Emma L. Tilston , Colin E. Snape , David. C. Apperley

○Quaternary Research

今回はなし

○Quaternary International

○Chemical Geology

特になし