Horizontal and vertical distributions of <Superscript>137</Superscript>Cs in seabed sediments around the river mouth near Fukushima Daiichi Nuclear Power Plant     

Tadahiko Tsuruta  Hisaya Harada  Toshiharu Misonou  Toshiyuki Matsuoka  Yasuyuki Hodotsuka 《Journal of Oceanography》2017,73(5):547-558

Investigations including a bathymetric survey, sonic prospecting, and vibrocoring were performed to understand the horizontal and vertical distribution of ¹³⁷Cs in seabed sediments in shallow seas with depths less than 30 m near the Fukushima Daiichi Nuclear Power Plant. Especially, features of ¹³⁷Cs distributions in deeper sections of the seabed sediments were studied to evaluate the vertical heterogeneity of ¹³⁷Cs distribution in the seabed sediments in shallow seas. The distribution area of the seabed sediments was less than half of the investigation area, and the locations of the seabed sediments were divided into flat and terrace-like seafloors based on their topographical features. The thicknesses of the seabed sediment layers were mostly <2 m. The ¹³⁷Cs inventories in the seabed sediments varied from 13 ± 1 to 3,510 ± 26 kBq m^?2, and continuous distributions of ¹³⁷Cs at depths greater than 81 cm were observed. The ¹³⁷Cs distributions were not uniform; however, the ¹³⁷Cs inventories tended to be larger near the base of the steeper ascending slopes than in the terrace-like seafloors themselves. Based on the relationship between the ¹³⁷Cs inventories and mean shear stress, features of the seafloor topography were inferred to be significant control factors governing the horizontal and vertical distribution of ¹³⁷Cs in the seabed sediments. Rapid changes and multiple peaks in the vertical profile of the ¹³⁷Cs distributions suggest that they are related to pulse input caused by heavy-rain events. Change in the ¹³⁷Cs inventories with depth in this study are larger than those reported in previous studies, indicating earlier results of ¹³⁷Cs inventories per unit in seabed sediments in shallow seas, especially near the river mouth, which drains a radiologically highly-contaminated basin, were underestimated.  相似文献   

Zircon U–Pb ages from tuff beds of the upper Mesozoic Tetori Group in the Shokawa district,Gifu Prefecture,central Japan†     

Nao Kusuhashi  Ai Matsumoto  Masaki Murakami  Takahiro Tagami  Takafumi Hirata  Tsuyoshi Iizuka  Takeshi Handa  Hiroshige Matsuoka 《Island Arc》2006,15(3):378-390

Abstract The upper Mesozoic Tetori Group contains numerous fossils of plants and marine and non‐marine animals. The group has the potential to provide key information to improve our understanding of the Middle Jurassic to Early Cretaceous biota of East Asia. However, the depositional age of the Tetori Group remains uncertain, and without good age constraints, accurate correlation with other areas is very difficult. As a first step in obtaining reliable ages for the formations within the Tetori Group, we used laser ablation‐inductively coupled plasma–mass spectrometry to measure the U–Pb ages of zircons collected from tuff beds in the Shokawa district, Takayama City, Gifu Prefecture, central Japan. The youngest reliable U–Pb ages from the tuff beds of the Ushimaru, Mitarai and Okurodani Formations are 130.2 ± 1.7, 129.8 ± 1.0 and 117.5 ± 0.7 Ma, respectively (errors represent 2 SE). These results indicate that the entire Tetori Group in the Shokawa district, which was previously believed to be correlated to the Upper Jurassic to Lower Cretaceous, is in fact correlated to the Lower Cretaceous. The maximum ages of the Ushimaru, Mitarai and Okurodani Formations are late Hauterivian to Barremian, late Hauterivian to Barremian and Barremian to Aptian, respectively.  相似文献   

Large-scale chaotically mixed sedimentary body within the Late Pliocene to Pleistocene Chikura Group, Central Japan     

Yuzuru  Yamamoto  Yujiro  Ogawa  Takayuki  Uchino  Satoru  Muraoka  Tae  Chiba 《Island Arc》2007,16(4):505-507

  相似文献   

The balloon observations of small cosmic X-ray bursts     

Y. Ogawara  M. Matsuoka  S. Miyamoto  N. Muranaka  J. Nishimura  M. Oda 《Astrophysics and Space Science》1976,42(1):211-216

In the record of the balloon observation which was performed on 27 September, 1970, a transient burst of X-rays was found. This event is concluded to be a cosmic gamma-ray burst of a smaller size or of a larger distance compared to the Vela bursts observed over the X-ray energy range. The energy spectrum is consistent with that of some of the Vela bursts. The time profile of the event is qualitatively similar to the 27 April, 1972 event studied by Apollo 16. The detection of small bursts over the X-ray energy range by the balloon observation during a period of the order of 10 to 100 h is not surprising considering a probable frequency-size distribution of the burst.Paper presented at the COSPAR Symposium on Fast Transients in X- and Gamma-Rays, held at Varna, Bulgaria, 29–31 May, 1975.  相似文献   

Damage assessment after 2001 Gujarat earthquake using Landsat-7 satellite images     

Yalkun Yusuf  Masashi Matsuoka  Fumio Yamazaki 《Journal of the Indian Society of Remote Sensing》2001,29(1-2):17-22

In this paper, we present a method of earthquake damage detection by comparing the optical images with panchromatic bands for the Gujarat, India earthquake, which occurred on January 26, 2001. The data used in this study are optical remote sensing images taken by Landsat-7 satellite on January 8 and February 29, 2001, before and after the earthquake. We have investigated the pre and post-earthquake satellite images calculating the differences in the reflection intensity (digital number) of the two images. The estimated affected area has been subtracted on a pixel unit based on the obtained frequency distributions of the differences in the optical sensor values, which show significant changes in the reflectance due to the earthquake disaster. We have investigated the accuracy of our analysis result using a classification method for the training areas with aerial photographs taken after the earthquake. The two damage detection methods show a very similar result.  相似文献   

Direct observation of frost wedging in alpine bedrock     

Norikazu Matsuoka 《地球表面变化过程与地形》2001,26(6):601-614

Width and temperature of rock joints were automatically monitored in the Japanese Alps. Three years of monitoring on a sandstone rock face shows two seasonal peaks of joint widening in autumn and spring. The autumn events are associated with short‐term freeze–thaw cycles, and the magnitude of widening reflects the freezing intensity and water availability. The short‐term freezing can produce wedging to a depth of at least 20 cm. The spring events follow a rise in the rock surface temperature to 0 °C beneath the seasonal snowcover, and likely originate from refreezing of meltwater entering the joint. Some of these events contribute to permanent enlargement of the joint. Two other joints on nearby rock faces experience only sporadic widening accompanying freeze–thaw cycles and insignificant permanent enlargement. Observations indicate that no single thermal criterion can explain frost weathering. The temperature range at which wedging occurs varies with the bedrock conditions, water availability and duration of freezing. Copyright © 2001 John Wiley & Sons, Ltd.  相似文献   

Lake-level changes during the past 100,000 years at Lake Baikal, southern Siberia   总被引：1，自引：0，他引：1  

Atsushi Urabe  Masaaki Tateishi  Hirokazu Matsuoka  Alexsander Dmytriev 《Quaternary Research》2004,62(2):214-222

Lake-level changes inferred from seismic surveying and core sampling of the floor of Lake Baikal near the Selenga River delta can be used to constrain regional climatic history and appear to be correlated to global climate changes represented by marine oxygen isotope stages (MIS). The reflection pattern and correlation to the isotope stages indicate that the topset and progradational foreset sediments of the deltas formed during periods of stable lake levels and warm climatic conditions. During warm stages, the lake level was high, and during cold stages it was low. The drop in the lake level due to cooling from MIS 5 through MIS 4 is estimated to be 33-38 m; from MIS 3 through MIS 2, it fell an additional 11-15 m. Because the lake level is chiefly controlled by evaporation and river input, we infer that more water was supplied to Lake Baikal during warm stages.  相似文献   

Diarrhetic shellfish poisoning in Narragansett Bay     

Lucie Maranda  Yuzuru Shimizu 《Estuaries and Coasts》1987,10(4):298-302

A two-year survey for diarrhetic shellfish poisoning (DSP) was conducted in Narragansett Bay using the mouse assay method. The suspected causative organisms,Dinophysis spp., were monitored at the same time. Only one shellfish sample, in September 1984, yielded an unequivocal positive result at a time when the dinoflagellate population was dominated byD. acuminata. False positive results were suspected in May, when the mussels appeared sexually matured, and in, the summer of 1985, at the time of an unusual massive picoplanktonic bloom. Evidence of toxin production byD. acuminata was obtained from an almost monospecific sample; we calculated that over 5.4×10⁵ cells would be necessary to produce one mouse unit. The specificity and sensitivity of the assay method are questioned and improvements for DSP detection are suggested.  相似文献   

Building community knowledge,resilience and resistance through research     

Matsuoka  Martha  Urquiza  John 《GeoJournal》2021,87(2):249-266

Skyrocketing housing costs in the U.S. have fueled research on gentrification, displacement, and neighborhood change, addressing how development processes impact low-income and working-class neighborhoods. Scholars have pointed to the importance of community-based knowledge in understanding the impact of gentrification at the neighborhood level (Chapple, Loukaitou-Sideris, Gonzalez, et al. 2017a; Chapple, Loukaitou-Sideris, Waddell, et al., 2017b) as well as how spatial knowledge informs organizing and activism of community-based organizations (Maharawal & McElroy, Annals of the American Association of Geographers, 108(2):380–389, 2018; Fields, Journal of Urban Affairs, 37(2):144–165, 2015; Elwood 2006a, The Professional Geographer, 58(2):197–208, 2006b). Despite the increasing research, less has centered on the knowledge of community organizers and residents in gentrifying neighborhoods and how community-driven mapping contributes to understanding of neighborhood level change from gentrification. This article presents a case study of community-driven research, analysis, and organizing of the Northeast Los Angeles Alliance (NELAA) a community-based member collective organization in Northeast Los Angeles with support of its academic partner Occidental College. The case study illustrates how community-driven research tied to organizing in the form of “countermapping” challenges the dominant practice and narrative of top-down property-centered development (Mahawaral and McElroy 2018). Further, the case study illustrates new ways to incorporate community knowledge into understanding of gentrification, displacement, and neighborhood change by: (1) introducing community-based collectives as particular types of community-based organizations utilizing community mapping and GIS; and, (2) illustrating detailed changes at the block and neighborhood levels by recognizing community-driven research and mapping as a source of in-depth and spatially specific historical knowledge and community vision.

  相似文献   

Jurassic and Lower Cretaceous radiolarian zonation in Japan and in the western Pacific   总被引：7，自引：0，他引：7  

Atsushi  Matsuoka 《Island Arc》1995,4(2):140-153

Abstract A radiolarian zonal scheme for the entire Jurassic and Lower Cretaceous using biostratigraphic data from both Japanese Island sections and the western Pacific seafloor is documented. The zonation is applicable to low and middle paleolatitude portions of the Paleo-Pacific ocean. Radiolarian bio-events such as the evolutionary first appearance biohorizon, first occurrence biohorizon, and last occurrence biohorizon were used to define zones. The 11 zones proposed are, in ascending order, Parahsuum simplum, Trillus elkhornensis, Laxtorum(?) jurassicum, Tricolocapsa plicarum, Tricolocapsa conexa, Stylocapsa(?) spiralis, Hsuum maxwelli, Pseudodictyomitra primitiva, Pseudodictyomitra carpatica, Cecrops sep-temporatus, and Acanthocircus carinatus zones. Preliminary age assignments for these zones are presented.  相似文献