BULLETIN OF THE GEOLOGICAL SURVEY OF JAPAN
Online ISSN : 2186-490X
Print ISSN : 1346-4272
ISSN-L : 1346-4272
Volume 58 , Issue 7-8
BULLETIN OF THE GEOLOGICAL SURVEY OF JAPAN
Showing 1-3 articles out of 3 articles from the selected issue
Article
  • Atsuyuki Ohta, Noboru Imai, Shigeru Terashima, Yoshiko Tachibana
    2007 Volume 58 Issue 7-8 Pages 201-237
    Published: November 30, 2007
    Released: May 17, 2014
    JOURNALS FREE ACCESS
    Sequential extraction is useful to assess the potential hazard of toxic metals and metal mobility in sediments. The extraction procedure developed by the Community Bureau of Reference (BCR) has been applied to the extraction of 51 elements from 30 stream sediments that were collected mainly for nationwide geochemical mapping in Japan. The geochemical reference samples, JSd-1,JSd-2 and JSd-3, were used to estimate the reproducibility of the elemental concentrations obtained using the BCR method. The BCR scheme is designed to extract elements in the intended phase using acetic acid (step 1), hydroxylammonium chloride (step 2), hydrogen peroxide and ammonium acetate (step 3), and hydrofluoric acid, perchloric acid, and nitric acid (step 4). The relative standard deviations of elemental concentrations in each extraction stage were generally less than ±10 - 25 %; the sums of elemental concentrations in respective steps (the total recoveries) ranged from 80 to 130 % of the bulk compositions in most cases. The extraction results for respective elements showed relative uniformity among the samples originated from various geological and lithological units, suggesting the limited influence of geology on the speciation of elements. In contrast, significant differences in the extraction results were found in samples from rural and urbanized areas even though they were all from sedimentary rock areas. Samples from urban areas were characterized by a higher proportion of Co, Ni, Zn and Cd extracted in step 1 and those of Cr, Cu, and Pb in step 3, probably indicating heavymetal contamination in their watersheds. Stream sediments near mining sites also showed a distinctive pattern in the extraction results. This study suggested that the BCR scheme is helpful for detecting the possible contamination of Cr, Ni, Cu, Zn, Cd, and Pb and exploring for mineral deposits bearing Zn, Cd and Pb.
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  • Hiroshi Kanaya, Shigeo Okuma
    2007 Volume 58 Issue 7-8 Pages 239-252
    Published: November 30, 2007
    Released: May 17, 2014
    JOURNALS FREE ACCESS
    About 340 granitic rock samples (including 12 gabbroic rock samples) exposed in the Abukuma Mountains, southern Tohoku region, were collected and measured on their physical properties such as density, porosity, magnetic susceptibility and natural remanent magnetization (NRM). Two tectonic lines, the Futaba Fracture Zone (FFZ) and Hatakawa Fracture Zone (HFZ) trend north in the east side of the Abukuma Mountains and the Tanagura Fracture Zone trends the NNW in the west side. Therefore, the Abukuma Mountains are divided into three areas by these tectonic lines. They are the east of the Futaba Fracture Zone, between of the Futaba Fracture Zone and the Hatakawa Fracture Zone, west of the Hatakawa Fracture Zone (between of the Hatakawa Fracture Zone and the Tanagura Fracture zone) and the South Area accompanied with metamorphic rocks. Eleven gabbroic rocks from the west of the HFZ and one from the South Area were collected and measured. The measurement result was averaged for each area.
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