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Clemens Reimann, Geological Survey of Norway (Norway)
Robert Garrett, Geological Survey of Canada (Canada)
David Smith, US Geological Survey (United States)
Xuejing Xie, Institute of Geophysical and Geochemical Exploration (China)
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The primary purpose of geochemistry is to determine quantitatively the chemical composition of the Earth and its parts, and to discover the laws that control the distribution of the individual elements. Applied geochemistry is the application of this knowledge to societal benefit, whether for discovering mineral resources, protecting the surface environment that sustains life, improving the efficiency of agriculture and animal husbandry, studying the behaviour of elements in the food-chain and their health effects on humans (epidemiology) and other biota, etc. All of these, to varying extents, depend upon knowledge of the spatial distribution of the elements in and on the Earth.
Modern regional geochemistry was born in the Soviet Union in the 1930s, and the basic methodologies for geochemical mapping had been developed by the late 1960s, with important extensions being made in the 1980s. The development of regional geochemical surveys, or mapping, in the context of spatial scale and transition from a mineral exploration and resource assessment tool to an environmental mapping exercise supporting multidisciplinary research is presented. Early surveys were generally high-density (multiple sample sites per km2), one-sample-material exercises. Currently, regional geochemical surveys employ a wide variety of sampling densities. These range from 1 sample site per 1 to 15 km2 for mineral exploration purposes to extremely low densities, e.g., 1 sample site per 2,500 to 10,000 km2, for national and international scale mapping projects. Furthermore, these latter mapping exercises are commonly multi-media to provide knowledge on the source, transport and fate of elements in the biogeochemical cycle.
Arthur Darnley's vision was for global-scale geochemical maps and data that could be used for environmental and resource management. We have progressed significantly towards that end since the start of IGCP Project 259 in 1988, 20 years ago now. The IUGS/IAGC Task Group on Global Geochemical Baselines, of which Arthur Darnley was the Honorary Chairman, continues as the international focus point. As applied geochemists we need to keep his vision before us and strive to complete the task along the path that he started us on.
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