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Regional-, national- and global-scale geochemical mapping projects have been carried out in China since the late 1970s. These geochemical mapping projects have provided high-quality data for both mineral resource investigations and environmental assessments. Four national-scale geochemical mapping projects in China are described here. (1) The Regional Geochemistry–National Reconnaissance (RGNR) project is China's largest national-scale geochemical mapping project and has covered more than 6 million km 2 of the country's hilly and mountainous regions since 1978. Generally, stream-sediment samples were collected at a density of 1 sample per km 2 and four samples were composited into one analytical sample for analysis of 39 elements. (2) The Deep-penetrating Geochemical Mapping (DEEPMAP) project has been conducted in covered terrains, including basins, at a density of 1 sample per 100 km 2 with analysis of 30–70 elements since 1994. In the past ten years, an area of approximately 800 000 km 2 has been covered. (3) The 76 Geochemical Element Mapping (76 GEM) project has been carried out since 1999. Approximately 1 million km 2 has been completed at present. (4) Multi-purpose eco-geochemical mapping projects have been conducted in the Quaternary plains of eastern China to provide data for environmental regulation and for improvement of agricultural practices since 1999. The data generated continue to play an important role in finding mineralization targets and ore deposits. China is also playing a leadership role in international geochemical mapping projects by transferring its expertise in sampling, chemical analysis and map generation to the developing countries through bilateral and multilateral collaboration. China is a leader in two large projects on a global scale: (1) the Environmental Geochemical Monitoring Network (EGMON) Project aims not only to have a quick overview of the geochemistry in China, but also to provide a pilot study for choosing the optimum sampling medium for geochemical mapping projects at a global scale; (2) the Geochemical Mapping Project uses delta and floodplain sediments of large rivers at a global scale.

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