DISTRIBUTION OF RARE EARTH ELEMENTS AND URANIUM IN VARIOUS COMPONENTS OF ORDINARY CHONDRITES     

Mitsuru Ebihara  Masatake Honda 《Meteoritics & planetary science》1984,19(2):69-77

Rare earth elements (REE) and uranium were studied for their distributions in various component phases of four ordinary chondrites, Kesen (H4), Richardton (H5), Bruderheim (L6), and Saint Séverin (LL6). A selective dissolution method was applied for the phase fractionation. The REE were analysed by neutron activation analysis, and U was determined by neutron-induced fission tracks. The present study revealed that both REE and U are highly enriched in the Ca-phosphate minerals with different enrichment factors, implying chemical fractionation between them. The phosphates seem to be responsible for more than 80% of the light REE in all chondrites. On the other hand, only 20–40% of the total U resides in the Ca-phosphates. This difference in enrichments might have been caused through the levels of metamorphic activity on the meteoritic parent bodies.  相似文献   

Halogens and noble gases in Mathematician Ridge meta-gabbros,NE Pacific: implications for oceanic hydrothermal root zones and global volatile cycles     

Mark A. Kendrick  Masahiko Honda  David A. Vanko 《Contributions to Mineralogy and Petrology》2015,170(5-6):1-20

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Fair Trade and organic initiatives confronted with Bt cotton in Andhra Pradesh,India: A paradox     

Rie Makita 《Geoforum》2012,43(6):1232-1241

This paper explores a confluence of Fair Trade and organic initiatives under the prevalence of Bt cotton in India, using as an interpretative framework Guthman’s conventionalization thesis for organic farming in the Northern context. In a case study conducted in Andhra Pradesh, the confluence of the two initiatives, contrary to their ethical standards, contributed to the spread of genetically modified (GM) seed. The Fair Trade initiative, lacking a scheme for compensating for the decrease in income that producers have to endure during the conversion period, tends to take a more relaxed attitude toward GM crops in order to assist small farmers. Fair Trade’s dilemma between helping poor farmers and promoting organic farming may have indirectly allowed Fair Trade producers to tend towards conventional farming with Bt seeds. As a result, the confluence of the two initiatives has not intensified the organic concept as “an alternative accumulation strategy for agrarian capitalism,” but neither has it released disadvantaged Southern farmers from agrarian capitalism. Rather, it has led farmers into another form of agrarian capitalism.  相似文献   

A simple semi-dynamic model of the subduction zone: effects of a moving plate boundary on the small-scale convection under the island arc     

Satoru Honda 《Geophysical Journal International》2008,173(3):1095-1105

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Ecological variations in diatom assemblages in the Paleo-Kathmandu Lake linked with global and Indian monsoon climate changes for the last 600,000 years     

Tatsuya Hayashi  Yoshihiro Tanimura  Yoshihiro Kuwahara  Masao Ohno  Mami Mampuku  Rie Fujii  Harutaka Sakai  Toshiro Yamanaka  Takeshi Maki  Masao Uchida  Wataru Yahagi  Hideo Sakai 《Quaternary Research》2009,72(3):377-387

Variations in fossil diatom assemblages and their relationship with global and Indian monsoon climate changes for the last 600,000 yr were investigated using a core of ancient lake (Paleo-Kathmandu Lake) sediments drilled at the Kathmandu Basin, Nepal Himalaya. Chronological scales of the core were constructed by tuning pollen wet and dry index records to the SPECMAP δ¹⁸O stack record. Examinations of biogenic silica contents and fossil diatom assemblages revealed that variations in productivity and compositions of diatom assemblages were closely linked with global and Indian monsoon climate changes on glacial and interglacial time scales. When summer monsoonal rainfall increased during interglacials (interstadials), diatom productivity increased because of increased inputs of terrestrial nutrients into the lake. When summer monsoonal rainfall reduced and/or winter monsoonal aridification enhanced during glacials (stadials), productivity of the diatoms decreased and lake-level falling brought about changes in compositions of diatom assemblages. Monospecific assemblages by unique Cyclotella kathmanduensis and Puncticulata versiformis appeared during about 590 to 390 ka. This might be attributed to evolutionary fine-tuning of diatom assemblages to specific lake environmental conditions. Additionally, low-amplitude precessional variations in monsoon climate and less lake-level changes may have also allowed both species to dominate over the long periods.  相似文献   

Presence of high nitrate to phosphate ratio subsurface water in the Tsushima Strait during summer     

Taketoshi Kodama  Akihiko Morimoto  Tetsutaro Takikawa  Masashi Ito  Yosuke Igeta  Shoko Abe  Ken-Ichi Fukudome  Naoto Honda  Osamu Katoh 《Journal of Oceanography》2017,73(6):759-769

To identify water with an excess nitrate concentration to phosphate ratio and its potential source, the nutrient concentrations in the Tsushima Strait (TSS) were investigated over ten cruises in August and September 2007–2014, excluding 2010. On the basis of the Redfield ratio, water with an excess nitrate concentration of >1 μM (positive ExNOx water) was identified below the surface mixed layer during four cruises in 2011–2013. Positive ExNOx water was present mainly in less-saline (<34) waters with a density of 22–25 σ _θ , and 25–75 m depth. However, in August 2012, positive ExNOx was detected in dense (25–25.5 σ _θ ) and deep (50–110 m depth) waters near the salinity maximum, although the salinity during this period was significantly lower than that in other years. The horizontal length of positive ExNOx water was >100 km across the TSS during two cruises in August 2012 and September 2013, respectively. According to multi-regression analysis conducted on the silicate concentration, temperature, and salinity, the silicate concentration was increased in the less-saline subsurface water. The required amount of original freshwater was 10^8–9 m³ day^?1 based on the excess nitrate concentration. This evidence indicates that the positive ExNOx water originated from large river waters such as the Changjiang. Thus, discharged water from the rivers of the East Asia is contributing to the increased N:P ratio in the Tsushima Warm Current, southern Japan Sea.  相似文献   

1-G model tests and hollow cylindrical torsional shear experiments on seismic residual displacements of fill dams from the viewpoint of seismic performance-based design     

Seda Sendir Torisu  Junichi Sato  Ikuo Towhata  Tsuyoshi Honda 《Soil Dynamics and Earthquake Engineering》2010

This paper concerns technological efforts for the general acceptance of performance-based seismic design principle of geotechnical structures. Among many problems to be solved, a particular emphasis was placed on the prediction of residual displacement that remains after a strong earthquake. Because of the complicated behavior of soils undergoing cyclic loading, the prediction is often either complicated/costly or not very accurate. The aim of this study is to examine the capability of existing prediction measures and propose some future scopes. To achieve these goals, shaking table model tests and laboratory shear tests were conducted by taking fill dams as an example target structure. It is concluded that performance-based design is possible if the necessary time and cost are spent and if the required accuracy of prediction is reasonable.  相似文献   

西北太平洋黑潮主轴区浮游有孔虫的垂直分布及其古海洋学意义   总被引：5，自引：0，他引：5  

徐学东  宇田理重  土桥正也  尾田太良 《第四纪研究》1999,19(6):502-510

我们对位于西北太平洋黑潮主轴区ＭＴＤ－０２站的１１个不同深度进行水平浮游拖网,并将采集到的活体浮游有孔虫(＞１２５μｍ)进行定量分析。结果表明,绝大多数活体浮游有孔虫生存于１００～２００ｍ以上的水体中,并集中分布于７５ｍ以上的水体。本站位８月份的最主要属种为：Ｇｌｏｂｉｇｅｒｉｎｏｉｄｅｓｒｕｂｅｒ,Ｇ．ｓａｃｃｕｌｉｆｅｒ,Ｎｅｏｇｌｏｂｏｑｕａｄｒｔｎａｄｕｔｅｒｔｒｅｉ和Ｇｌｏｂｉｇｅｒｉｎｉｔａｇｌｕｔｉｎａｔａ。次主要属种为Ｇｌｏｂｉｇｅｒｉｎｅｌｌａ　ａｅｑｕｉｌａｔｅｒａｌｉｓ,　ｇｌｏｂｉｇｅｒｉｎａｂｕｌｌｏｉｄｅｓ,Ｐｕｌｌｅｎｉａｔｉｎａｏｂｌｉｑｕｉｌｏｃｕｌａｔａ,Ｇｌｏｂｏｒｏｔａｌｉａｔｒｕｎｃａｔｕｌｉｎｏｉｄｅｓ,Ｏｒｂｕｌｉｎａｕｎｉｖｅｒｓａ和Ｇ．ｃｏｎｇｌｏｂａｔｕａ。这些种在不同的深度其产出量大不相同,但绝大多数均在叶绿素最为丰富的２５ｍ处显示出最大值。这表明食物来源是控制浮游有孔虫在ＭＴＤ－０２站垂直分布的最主要因素。另外,Ｇｌｏｂｉｇｅｒｉｎｅｌｌａａｅｑｕｉｌａｔｅｒａｌｉｓ和Ｐｕｌｌｅｎｉａｔｉｎａｏｂｌｉｑｕｉｌｏｃｕｌａｔａ两个种在温跃层的底部５０ｍ处显  相似文献   

Short introduction to the K2S1 project     

Makio C. Honda 《Journal of Oceanography》2016,72(3):341-342

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Statistical Estimation of the Production of Cosmic-Ray-Induced Nuclides in Meteorites*     

Masatake Honda 《Meteoritics & planetary science》1988,23(1):3-12

Abstract— Among iron meteorites there is a simple relationship estimating, with two parameters, the production rates of spallation products of mass A, that range in ΔA from 2 to 36 (Cr to Ne), where ΔA is 56 — A. This paper describes further applications of this relation, extending it to chondrites, in terms of the effective ΔA. It is possible to systematize the production of common products in chondrites such as ³He, ²⁶Al,²²Ne, ²¹Ne and ³⁸Ar. For this purpose, data on products determined in the metal phases of chondrites are useful in correlating stones to irons. For general application to stone meteorites, statistical treatments for multielement target systems are employed, except for the lowest energy reaction products. Statistical methods for spallation products are thus now applicable for all iron and stone meteorites.  相似文献