Global geochemical mapping-Historical development and suggestions of future work

Abstract：Great progress has been made in regional and national geochemical mapping. How to use extremely low-density sampling to obtain a global picture of the distribution of most elements in the periodic table in the expectable future is an important issue for applied geochemists. This will depend on the innovation of the mapping concept and developments of new sample media, sampling layout and sampling methodology. English geochemists found that the analytic results of stream sediment samples taken from estuaries of catchments covering an area of several to several dozen square kilometers approximate the average values of elements in soils in catchments in the upper reaches of the rivers. This finding has been extended by Norwegian and Chinese geochemists who analyzed samples taken from overbank and floodplain sediments at the estuaries of still larger rivers (whose catchments are several hundred, thousand and even a few dozen thousand square kilometers). Such a new finding is in accordance with the fractal concept, which may be further extended to main estuaries of some catchments with an area up to hundreds of thousands of or over a million square kilometers in the world. However, more research should be carried out. Based on this new mapping concept, a proposal of the project “Global Geochemical Mapping and Sediment-Associated Flux of Major World Rivers” was advanced.