Vol.3 No.4 2011

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Research paper−268−Synthesiology - English edition Vol.3 No.4 pp.268-279 (Mar. 2011) 2.2 PurposeThe purposes of the geochemical map are mainly classifiable as two (Fig. 1). The first is to provide basic geochemical information about the land of Japan. Information about the distribution and movement of elements in the surface of the earth are basic data supporting all discussions related to earth science such as the origin of rock or the formation of the Japanese islands. That information is the basis for the research of earth sciences, which are undertaken to study what elements exist and where they are distributed. It is also important to know the regional elemental concentration or the average chemical composition of a larger area. For example, the average chemical composition of Japan is the most basic information, showing what elements make up the Japanese islands. Another example is the natural radiation dose, as estimated from the concentrations of uranium and thorium on the Earth’s surface. As a scientific application, the geochemical map is used to estimate the natural background radiation dose using a liquid scintillation device (KamLAND) for neutrino measurements at Kamioka in Gifu Prefecture. Here, the dose is inferred from the concentrations of the uranium and thorium on the Earth’s surface, as obtained from the geochemical map[1].The second purpose is to address environmental problems. The geochemical map provides the key to clarification of the soil and marine pollution by industrial or factory wastes. To evaluate such pollution, it is important to obtain the natural background, which is then used as a baseline of pollution and the distribution of toxic elements. However, such an investigation has remained limited to small regions. 1 IntroductionWhat elements exist in our surroundings and what are the concentrations of those elements? Such basic knowledge has not been understood until recently. And such knowledge has not been readily accessible. A geochemical map enables anyone to understand this valuable information visually at one view. For example, when discussing soil and marine pollution, which have become severe problems, such a tool will become a key to infer the distribution of toxic elements such as arsenic, mercury, and cadmium. This paper describes how the nationwide geochemical map in Japan was first planned, and then how it was actually made and used.2 Background and purpose of the geochemical map2.1 What is a geochemical map?A geochemical map is a distribution map of elemental concentrations on the surface of Earth (surface of the Earth’s crust). Figure 1 depicts what factors determine the distributions of elements. The most important of them is what kinds of rock and sediment are distributed in the region. This is a natural background. Additionally, influences from industrial, agricultural and urban life activities are important influences. The actual distributions of the elements constitute the sum of these various factors. In other words, for pollution, we should consider these factors in comparison with the natural background.- Geochemical map of land and sea of Japan-Noboru ImaiInstitute of Geology and Geoinformation, AIST Tsukuba Central 7, 1-1-1 Higashi, Tsukuba 305-8567, Japan E-mail : Original manuscript received May 13, 2010, Revisions received September 4, 2010, Accepted September 8, 2010A geochemical map of the whole of Japan has been drawn for the first time by surveying the distribution of elements in land and sea throughout Japan. This map revealed the natural background of the elements distribution and allows us to know the continuous flow of elements from land to sea. The samples used in this work are 3024 riverbed sediments and 4905 seabed sediments, and 53 elements including toxic elements of As, Hg, Cd, etc. have been analyzed. In this research, a new survey method has been established for a certain district at first and then it has been applied to the whole of Japan with modification taking realistic operability into consideration, and the object has been extended from land, sea to soil. The geochemical map is also used for evaluating the pollution of soils and marine sediments resulting from human and industrial activities. The results have been made public through publication and website and have had various social impacts. In this paper, the research scenario adopted to compose the geochemical map of Japan is first described, then a series of research processes are described starting from material sampling and treatment chemical analysis, measurement of element concentration, composition of geochemical map to data release.Investigation of the distribution of elements of the whole of Japan and their applicationsKeywords : Geochemical map, distribution of elements, toxic elements, environmental pollution[Translation from Synthesiology, Vol.3, No.4, p.281-291 (2010)]

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