Masao Uchida

Tokyo Medical Center

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Yasuyuki Shibata

National Institute for Environmental Studies

Miyuki Kondo

Prefectural University of Hiroshima

Ryuji Tada

The University of Tokyo

Minoru Yoneda

The University of Tokyo

Naomi Harada

Japan Agency for Marine-Earth Science and Technology

Takuya Itaki

Geological Survey of Japan

Katsumi Yoshino

Shimane Institute for Industrial Technology

S. Rella

National Institute for Environmental Studies

Masatoshi Morita

Gifu Shotoku Gakuen University

Ken’ichi Ohkushi

Kobe University

Cooperative Institutions

University of Arizona

227

The University of Tokyo

132

National Institute for Environmental Studies

Hokkaido University

Tohoku University

Chinese Academy of Sciences

Nagoya University

Kyoto University

Centre National de la Recherche Scientifique

Institut de l'Information Scientifique et Technique

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Millennial-scale variability of East Asian summer monsoon inferred from sea surface salinity in the northern East China Sea (ECS) and its impact on the Japan Sea during Marine Isotope Stage (MIS) 3

Progress in Earth and Planetary Science (2019)

Yoshimi Kubota Katsunori Kimoto Ryuji Tada Masao Uchida Ken Ikehara

Color alternations in deep-sea sediment in the Japan Sea have been thought to be linked to millennial-scale variations in the East Asian summer monsoon (EASM), associated with the Dansgaard-Oeschger (D-O) cycles and Heinrich events in the high-latitude North Atlantic during Marine Isotope Stage 3 (MIS 3). In this study, we investigate the variability of sea surface salinity (SSS) in the northern East China Sea (ECS) to evaluate the EASM precipitation in South China and its linkage to the sediment color of the Japan Sea during MIS 3. High time resolution (< 100 years) SSS along with sea surface temperature (SST) records were reconstructed using paired Mg/Ca and the oxygen isotope of planktic foraminifera Globigerionoides ruber sensu stricto from core KR07-12 PC-01 recovered from the northern ECS. The results indicate that millennial-scale variability of the SSS is observed with the amplitude of ~ ± 1 during MIS 3. The variations in SSS are well correlated to D-O cycles and Heinrichs. The EASM precipitation decreases in association with the southward shift of the westerly jet in D-O stadials and Heinrichs, suggesting suppressed moisture convergence along the EASM front associated with weakened North Pacific subtropical high in response to the slow-down of the Atlantic Meridional Overturning Circulation. In a comparison between the SSS in the ECS and the color alternation in the Japan Sea, closely correlated variations between the two records in the interval 44–34 ka indicate that the SSS in the ECS plays a crucial role in regulating nutrient and salinity inflow into the Japan Sea. However, the linkage becomes ambiguous, especially after ~ 30 ka, when the sea level falls toward the level of the last glacial maximum. This shift is associated with changes in sediment facies, confirming that the underlying mechanism in regulating the sedimentary change in the Japan Sea depends on the sea level.

Stadial

Marine isotope stage

East Asian Monsoon

10.1186/s40645-019-0283-0

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Citations (17)

Characteristics of alkenones synthesized by a bloom of emiliania huxleyi in the Bering Sea

Geochimica et Cosmochimica Acta (2003)

Naomi Harada Kyung‐Hoon Shin Akihiko Murata Masao Uchida T. Nakatani

Alkenone

Emiliania huxleyi

Haptophyte

Bloom

Degree of unsaturation

10.1016/s0016-7037(02)01318-2

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Citations (105)

Transient response of mid-depth circulation in the northwest Pacific around the Younger Dryas event inferred from AMS 14C ages of foraminifera

Nuclear Instruments and Methods in Physics Research Section B Beam Interactions with Materials and Atoms (2004)

Naokazu Ahagon Masao Uchida

Circulation (fluid dynamics)

Transient (computer programming)

10.1016/j.nimb.2004.04.088

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Citations (4)

Simulating soil carbon dynamics in Alaskan terrestrial ecosystems

Japan Geoscience Union (2015)

Xin Wang Masayuki Yokozawa Hazuki Arakida Kensuke Mori Takesi Ise

Terrestrial ecosystem

Soil carbon

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A Southern Ocean trigger for Northwest Pacific ventilation during the Holocene

Japan Geoscience Union (2014)

S. Rella Masao Uchida

Holocene ocean circulation is poorly understood due to sparsity of dateable marine archives with submillennial-scale resolution. Here we present a record of mid-depth water radiocarbon contents in the Northwest (NW) Pacific Ocean over the last 12.000 years, which shows remarkable millennial-scale variations relative to changes in atmospheric radiocarbon inventory. Apparent decoupling of these variations from regional ventilation and mixing processes leads us to the suggestion that the mid-depth NW Pacific may have responded to changes in Southern Ocean overturning forced by latitudinal displacements of the southern westerly winds. By inference, a tendency of in-phase related North Atlantic and Southern Ocean overturning would argue against the development of a steady bipolar seesaw regime during the Holocene.

Westerlies

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Mid‐depth circulation in the northwest Pacific during the last deglaciation: Evidence from foraminiferal radiocarbon ages

Geophysical Research Letters (2003)

Naokazu Ahagon Ken’ichi Ohkushi Masao Uchida Tomokazu Mishima

Sediment cores (MR01‐K03 PC4/PC5, 1366 m water depth) collected from off northern Japan were studied using coexisting planktonic and benthic foraminiferal radiocarbon measurements to reconstruct the history of mid‐depth circulation in the northwest Pacific. Reconstructed ventilation ages indicate that, consistent with data from a previous radiocarbon study at a shallower site, there was significant variation in mid‐depth circulation during the last deglaciation, especially in the Bølling‐Allerød (13–15 ka) and Younger Dryas (11.5–13 ka) intervals. Our record indicates that the ventilation changes in the North Pacific were antiphase to those of the North Atlantic, suggesting that atmospheric moisture transport associated with the Asian Monsoon might have played a great role in millennium‐scale ventilation changes in the North Pacific during the last deglaciation.

Deglaciation

10.1029/2003gl018287

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Citations (89)

A Southern Ocean trigger for Northwest Pacific ventilation during the Holocene?

Scientific Reports (2014)

S. Rella Masao Uchida

Westerlies

10.1038/srep04046

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Citations (20)

Compound-Specific Radiocarbon Ages of Fatty Acids in Marine Sediments from the Western North Pacific

Radiocarbon (2001)

Masao Uchida Yasuyuki Shibata Kimitaka Kawamura Yuichiro Kumamoto Minoru Yoneda

Compound-specific radiocarbon analysis of five fatty-acid biomarkers was conducted for marine sediments collected from the western North Pacific. The fatty acids (C 12 to C 34 ) showed a typical bimodal distribution pattern with two maxima at C 16 and C 26 . Their carbon isotopic compositions ranged from −25.1‰ (C 16 ) to −31.8‰ (C 28 ), suggesting that they derived from terrestrial higher plants and marine organisms. A large variations of 14 C ages were found among the fatty acids detected in the same sedimentary horizon of the core, ranging from 530 BP (C 18 ) to 3250 BP (C 28 ). The results of 14 C analysis of fatty acids could be divided into two groups, i.e., lower molecular weight (LMW) fatty acids (C 16 , C 18 ) derived from marine organisms and higher molecular weight (HMW) fatty acids (C 24 , C 26 , C 28 ) derived from terrestrial higher plants. The HMW fatty acids showed older ages, ranging from 2550 BP (C 24 ) to 3250 BP (C 28 ), than LMW fatty acids (530 BP [C 18 ] to 1,820 years BP [C 16 ]). On the other hand, bulk-phase total organic matter (TOM) showed the age of 2260 BP that is between those two groups, suggesting that it was likely a mixture of organic matter derived from marine and terrestrial sources. The compound specific 14 C ages and δ 13 C data of sedimentary fatty acids presented here could provide useful information to decipher the fate and transport process of terrestrial organic matter to marine sediments.

Sedimentary organic matter

10.1017/s0033822200041618

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Citations (38)

A new application of radiocarbon (14C) concentrations to stream food web analysis

Nuclear Instruments and Methods in Physics Research Section B Beam Interactions with Materials and Atoms (2009)

Naoto Ishikawa Masao Uchida Yasuyuki Shibata Ichiro Tayasu

Detritus

Isotope Analysis

Terrestrial ecosystem

δ15N

Carbon fibers

10.1016/j.nimb.2009.10.127

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Citations (18)

Identification of Volatile Selenium Compounds Produced in the Hydride Generation System from Organoselenium Compounds

Analytical Chemistry (2001)

Amit Chatterjee Yasuyuki Shibata Minoru Yoneda Rupendranath Banerjee Masao Uchida

We report a novel aqueous derivatization of selenomethionine (Semet), selenoethionine (Seet) and trimethylselenonium ion (TmSe) by NaBH4 and HCI to volatile selenium species, namely, diethyldiselenide (DeDSe), dimethyldiselenide (DMDSe), dimethylselenide (DmSe) and ethylhydrogenselenide (ESeH), in the hydride generation (HG) system. The volatile selenium compounds produced in the HG system were on-line trapped and concentrated in a U-tube that was immersed in the liquid nitrogen trap. The trapped volatile Se compounds were volatilized at 80 degrees C in a water bath, and 50-500 microL of volatile gas was injected into the GC/AED and GC/MS, respectively. It has been established that DmSe, DmDSe, and DeDSe are the predominant Se compounds that are produced in the HG system from TmSe, Semet, and Seet, respectively, followed by ESeH from Seet. Analytical methods previously employed have stated that these compounds are inactive in the HG system. Prior decomposition of Semet, Seet, and TmSe to selenous acid is essential before HG. To the best of our knowledge, current findings for the production and identification of volatile selenium compounds in the HG system are new and different from existing reports; hence, direct estimation of Semet, Seet, and TmSe is possible when coupling with a HG system using a suitable Se-specific detector.

Mercury

10.1021/ac001356w

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Citations (43)