Vol.3 No.4 2011

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Research paper : Investigation of the distribution of elements of the whole of Japan and their applications (N. Imai)−270−Synthesiology - English edition Vol.3 No.4 (2011) the public of the geochemical map of Japan. As factors affecting the production of a geochemical map, elemental distribution, elemental abundance, crust surface, kind of element, kind and collection density of sample, land or sea, representativeness of samples, processing of sample, chemical analysis, media to the public, drawing and standardization of data, system of research and analysis, standardization of method were considered, as shown in the figure. These basic factors for fabricating a geochemical map can be unified further as five components: basic characteristics, completeness, reliability, user convenience, and operability. Each of these components becomes a basis for the geochemical map. The final goal is the formation and public presentation of a geochemical map of all Japan, in which the sea and land maps are unified.Figure 4 depicts the history of the geochemical map in AIST. It was the first time for us to produce a geochemical map systematically for the northern Kanto region, although the geochemical exploration to find mineral deposits had been conducted in AIST for a long time up to that time. The purpose of the project was the construction of techniques and methodology as a first step to our assessment of chemicals throughout the whole country. Then, the geochemical map of Sendai and Yamagata, and the coast of Sea of Japan (from Hokuriku to Akita) were made in respective projects. Subsequently, the geochemical map of land of the whole country was completed. As the next step, a nationwide geochemical map of the sea was fabricated as an extension of the land map. Then the nationwide geochemical map of land and sea was completed. At present, a nationwide geochemical map of soils is being developed as an additional resource.4.1.1 Geochemical map of northern Kanto (Seeking to build and develop the methodology)The Geological Survey of Japan (GSJ) compiled a geochemical map of the northern Kanto region from Mito to Iwaki in 1991, as described above[10][11]. The motivation for starting the project was the completion of the British geochemical map of the U.K., which was published and which subsequently caused a huge impact on studies there and abroad. The simplicity and strong impression of the map are noteworthy: any map user can survey the elemental distribution of the entire U.K. easily by color. The technique was geochemical exploration seeking ore deposits, which was the same goal as that pursued by the geochemistry group of GSJ up to that time. The project of geochemical map started as a large project with high expectations; all groups related to geochemistry cooperated to produce maps jointly at that time.In the geochemical map of the northern Kanto region, 3850 stream sediment samples were collected from the area of about 4000 km2 (the sampling density was one sample to about 1 km × 1 km). At the project’s outset, it was an important problem that this huge number of samples had to be collected. Eventually, 7–8 researchers and more than 20 assistants (students) formed several teams. The samples were collected during the first two weeks of the summer Fig. 2 Scheme of making the geochemical mapThe figure shows the workflow from sampling to drawing the geochemical map by GIS, samples used for this study, stream sediments and marine sediments, sample treatments, chemical analysis, and drawing the geochemical map.Draw geochemical mapICP, AAS measurementSieving, Powdering,Digestion by acid,Fractional dissolutionStream sediment,Marine sediment, SoilDrawing map by GISMeasurementChemicalanalysisSampleprocessingSamplingStream sedimentMarine sedimentSampling of stream sedimentSampling of marine sedimentSampleprocessingSampleprocessingAnalysis,DrawingAnalysis,DrawingGeochemical map of landGeochemical map of seaSievingSievingDryingDryingSeparation ofmagnetic mineralsSeparation ofmagnetic mineralsChemicalanalysisChemicalanalysisDrawingDrawingChemicalanalysisChemicalanalysisDrawingDrawingCrushingCrushingDryingDrying

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