A5078611331- Geology and Paleoclimatology Research
- Methane Hydrates and Related Phenomena
- Isotope Analysis in Ecology
- Geological formations and processes
- Paleontology and Stratigraphy of Fossils
- Marine and environmental studies
- Geochemistry and Elemental Analysis
- Cryospheric studies and observations
- Marine and coastal ecosystems
- Hydrocarbon exploration and reservoir analysis
- Geological and Geochemical Analysis
- Geomagnetism and Paleomagnetism Studies
- Pacific and Southeast Asian Studies
- Geological Studies and Exploration
- Archaeology and ancient environmental studies
- earthquake and tectonic studies
- Geological and Geophysical Studies
- Winter Sports Injuries and Performance
- Marine Biology and Ecology Research
- Maritime and Coastal Archaeology
- Geochemistry and Geologic Mapping
- Oceanographic and Atmospheric Processes
- Karst Systems and Hydrogeology
- Polar Research and Ecology
- Groundwater and Isotope Geochemistry
University of Toyama
2016-2025
International Ocean Discovery Program
2021
United States Office of Personnel Management
2021
Sam Houston State University
2021
University of Plymouth
2021
Geological Survey of Western Australia
2021
Tongji University
2021
Discovery Place
2021
Texas A&M University
2021
Graduate School USA
2015-2018
Research Article| May 01, 2010 Intermediate water formation in the Bering Sea during glacial periods: Evidence from neodymium isotope ratios Keiji Horikawa; Horikawa * 1Graduate School of Environmental Studies, Nagoya University, Furo-cho, Chikusa-ku, 464-8601, Japan *E-mail: horikawa@nagoya-u.jp. Search for other works by this author on: GSW Google Scholar Yoshihiro Asahara; Asahara Koshi Yamamoto; Yamamoto Yusuke Okazaki 2JAMSTEC (Japan Agency Marine-Earth Science and Technology), 2-15...
Abstract Warming of high northern latitudes in the Pliocene (5.33–2.58 Myr ago) has been linked to closure Central American Seaway and intensification North Atlantic Deep Water. Subsequent cooling late may be related effects freshwater input from Arctic Ocean via Bering Strait, disrupting Water formation enhancing sea ice formation. However, timing freshening not defined. Here we present neodymium lead isotope records detrital sediment Sea for past 4.3 million years. Isotopic data suggest...
Abstract. We reconstructed the ventilation record of deep water at 2100 m depth in mid-latitude western North Pacific over past 25 kyr from radiocarbon measurements coexisting planktic and benthic foraminiferal shells sediment with a high sedimentation rate. The 14C data on fragile robust were concordant each other, ensuring quality record. activity changes consistent atmospheric record, suggesting that no massive mixing old carbon abyssal reservoir occurred throughout glacial to deglacial periods.
The Last Interglacial (LIG: 130,000-115,000 years ago) was a period of warmer global mean temperatures and higher more variable sea levels than the Holocene (11,700-0 ago). Therefore, better understanding Antarctic ice-sheet dynamics during this interval would provide valuable insights for projecting sea-level change in future warming scenarios. Here we present high-resolution record constraining changes Wilkes Subglacial Basin (WSB) East Antarctica LIG, based on analysis sediment provenance...
The n -alkane C 31 /(C 29 +C ) ratios from surface sediments in the eastern equatorial Pacific (EEP) exhibit higher values to north and lower south across southern edge (2–4°N) of Intertropical Convergence Zone (ITCZ). Since plants tend synthesize longer chain length -alkanes response elevated temperature and/or aridity, + 31) at northern sites suggest a contribution vegetation under hot dry conditions. This is consistent with observation that receive levels plant waxes transported by...
A novel exopolysaccharide-producing bacterium, designated strain SE3 T , was isolated from Pacific Ocean sediment. The Gram-stain-negative, motile, strictly aerobic, oxidase-positive and catalase-positive, required Na + for growth. Its major isoprenoid quinone ubiquinone-8 (Q-8), its cellular fatty acid profile mainly consisted of C 16 : 1 ω7 c 0 18 . DNA G+C content 46.9 mol%. 16S rRNA gene sequence analysis suggested that is a member the genus Pseudoalteromonas Strain exhibited close...
The paired analyses of the Mg/Ca ratio and oxygen isotopic composition (δ 18Oc) surface-dwelling planktonic foraminifera have become a widely used method for reconstructing ambient seawater 18Osw) as robust proxy surface salinity. Globigerinoides ruber (G. ruber) is mixed-layer dweller, its fossil shell an ideal archive recording past sea water conditions, such those caused by variability in East Asian summer monsoon (EASM). Here, we investigate validity shell-derived δ 18Osw estimates G....
Abstract Oxygen isotope ratios (δ 18 O) and Mg/Ca in organically produced calcium carbonate (calcite aragonite) by marine species have been used as proxies for paleotemperature. The relationship between the components of large benthic foraminiferal tests (high‐magnesium calcite) seawater temperature has little investigated yet. We conducted culture experiments using two reef‐dwelling foraminifera under six conditions (21–30°C). selected perforate Calcarina gaudichaudii , imperforate...
The stability of the West Antarctic Ice Sheet (WAIS), crucial for preventing major future sea-level rise, is threatened by ocean-forced melting in Pacific sector, especially Amundsen Sea. So far, direct evidence extent and rate WAIS retreat during past warm periods has been lacking. Here, we analyzed detrital Nd, Sr, Pb isotope data sediments ( 18.93 206Pb/204Pb) low eNd (< &#8211;5 eNd) values. This distinct isotopic signature suggests long-distance supply detritus sourced from...
We investigate the suitability of radiolarian species as palaeoceanographic proxies in Northwest Pacific Ocean using 33 new core-top samples collected since 2021 during Joint Usage/Research Center for Atmosphere and Science (JURCAOS, Japan), combined with existing datasets published by authors this study. The main target study is to review a paleoceanographic proxy develop robust methodology estimate past Sea Surface Temperature based on abundances. For purpose, we compiled our data from...
Although cis-diamminedichloro-platinum (CDDP) exhibits strong therapeutic effects in cancer chemotherapy, its adverse such as peripheral neuropathy, nephropathy, and vomiting are dose-limiting factors. Previous studies reported that chronotherapy decreased CDDP-induced nephropathy vomiting. In the present study, we investigated influence of dosing times on neuropathy rats. CDDP (4 mg/kg) was administered intravenously at 5:00 or 17:00 every 7 days for 4 weeks to male Sprague–Dawley rats,...
The orbital-scale variability of the Indian summer monsoon (ISM) has been influenced by multiple factors, such as atmospheric CO2 concentration, global ice volume, and insolation. Proxies for weathering activity paleo-productivity provide potential insights into driving forces its variability. We documented multi-proxy data at IODP Site U1445, located in Mahanadi Basin northwestern Bay Bengal, to find out ISM over last 200 ka. proxy records, Nd/Sr isotopes detrital particles, clay mineral...
Abstract The East China Sea (ECS) is one of the largest marginal seas in world with high primary productivity and a large area low dissolved oxygen. This study observed low‐oxygen bottom water on outer‐edge shelf ECS summer seasons 2018–2020. contributions various masses to waters were quantified, interaction between Kuroshio was validated by mixing model using heavy rare earth elements (HREEs) together potential temperature, salinity. For further reliability verification, tracers such as δ...
Research Article| September 11, 2018 Late Miocene–mid-Pliocene tectonically induced formation of the semi-closed Japan Sea, inferred from seawater Nd isotopes Yukiko Kozaka; Kozaka 1Graduate School Science and Engineering for Education, University Toyama, Gofuku 3190, Toyama 930-8555, Search other works by this author on: GSW Google Scholar Keiji Horikawa; Horikawa * 2Graduate Research, *E-mail: horikawa@sci.u-toyama.ac.jp Yoshihiro Asahara; Asahara 3Department Earth Environmental Sciences,...
Abstract 87 Sr/ 86 Sr ratios and εNd values of detrital particles at International Ocean Discovery Program (IODP) Site U1456 in the Laxmi Basin Arabian Sea were measured to trace changes sediment provenance over glacial–interglacial cycles. Based on correlation planktonic foraminiferal ( Globigerinoides ruber ) δ 18 O fluctuations with LR04 stack benthic foraminifera values, combined shipboard biostratigraphic palaeomagnetic data, studied interval spans ∼1.2 Ma. Over past 800 ka, ranged from...