1.1 General

Research conducted since 1988 as part of the International Geochemical Mapping (IGM) project has confirmed that the presently available data concerning the geochemical composition of the Earth's surface are substantially incomplete and internally inconsistent. Many of the older data sets have seroius deficiencies and do not meet basic requirements for establishing the range of natural geochemical background values. As a result of natural geological and environmental processes, element abundances in natural materials can vary by several orders of magnitude within short distances. These variations are inadequately documented and their existence is often overlooked in the setting of public policy.

A high quality geochemical database is pertinent to a wide range of investigations in the earth and life sciences, and should be considered as an essential component of environmental knowledge. Detailed information about the natural variability of the geochemical background is pertinent to administrative and legal issues as much as to scientific research. Sustainable long-term management of environmental and mineral resources is dependant upon a comprehensive and reliable database. The International Geosphere-Biosphere Program on Global Change requires information on current conditions. Important aspects of change cannot be measured, or their consequences anticipated. unless the present composition of the earth's surface materials is known. To quote a recent Global Change Report (IGBP, 1992),

"The availability of data and how they will be managed are two critical facets of future global change research. Global science is data-lomited, and therefore new efforts must be engaged which foster the development and validation of global data sets."

TheInternational Geochemical Mapping project, which was endorsed in 1988 as a contribution to the IGBP (IGBP, 1989), is a multi-stage project established to consider how best to provide quantitative data to portray the geochemical diversity of the earth's land surface.

Participants in IGCP 259 have undertaken a comprehensive review of methods of regional and national geochemical mapping and examined the results obtained. Many problems have been identified and a variety of solutions discussed. Field and laboratory research has been carried out. The resulting recommendations are contained in this report. They are directed towards geochemists and those institutions which have a mandate for providing an earth science and/or environmental database.

The recommendation stem from the conviction that, since geochemical phenomena extend across national borders, and the related information base has multi-purpose, multi-national applications, it is logical, desirable and advantageous to:

(a) establish a common primary database at an international level, and (b) provide a framework for the adoption of standardized methods and reference materials for detailed regional or national mapping.

These will provide a recognized quantitative base for more specialized local investigations to answer particular environmental and economic problems concerning animal and human health, soil fertility, agriculture, forestry, water supply and irrigation, waste disposal, mineral exploration and mining, industrial pollution and land-use in general.

The detailed recommendations which have been prepared relate to the establishment of a global network of geochemical reference samples; sample collection and preparation specifications; analytical requirements and standards; gamma radiation methods applicable to natural and man-made radioelements; and data management procedures. An appendix contains information to assist readers in developing countries who may not have easy access to supplementary technical literature. Implementation of these recommendations will make it possible to assemble geochemical baseline data for all non-gaseous elements on a systematic global basis. A world geochemical atlas will be one of many possible products which can be derived from these data. The authors of this report believe that a Global Geochemical Database is a necessary and exigent investment for mankind. The cost of establishing the proposed reference network is estimated to be in the range of US$300-400 million, about equal to the cost of launchimg one NASA Space Shuttle flight.』