The G-BASE programme involves systematic sampling and the determination of chemical elements in samples of stream sediment, stream water and soil, to build up a picture of the surface chemistry of the UK. The average sample density for stream sediments and water is about one site per 1.5-2km square, and for soils one site per 2km square. Analytical precision is high with strict quality control to ensure countrywide consistency. Results have been standardised to ensure seamless joins between geochemical sampling campaigns. The data provide baseline information on the natural abundances of elements, against which anomalous values due to such factors as mineralisation and industrial contamination may be compared. Analytical data for the 150 microns fraction of soil and stream sediment samples are available for some or all of: Ag, As, B, Ba, Bi, Be, Ca, Ce, Cd, Co, Cr, Cs, Cu, Fe, Ga, K, La, Li, Mg, Mn, Mo, Nb, Ni, P, Pb, Rb, Sb, Se, Sn, Sr, Th, Ti, U, V, Y, Zn, and Zr. Most water samples have been analysed for alkalinity, pH, conductivity, F and U and some for multi-element analyses including Al, Cl, Na, Si, SO4,NO4, and TOC. The project now routinely determines the elements listed in the <2mm fraction of surface soils.

This layer shows data collected mainly by the Geochemical Baseline Survey of the Environment (G-BASE) programme. Geochemical data are available for soil samples for the Humber-Trent and East Anglia atlas areas (see the Geochemical atlas areas layer). Samples for East Midlands and part of Southeast England have been collected and are currently either undergoing analysis or data conditioning. More than twenty urban areas have also been sampled and top soil analyses are available for these urban areas (Belfast, Cardiff, Corby, Coventry, Derby, Doncaster, Glasgow, Hull, Ipswich, Leicester, Lincoln, Manchester, Mansfield, Northampton, Nottingham, Peterborough, Scunthorpe, Sheffield, Swansea, Stoke, Telford, Wolverhampton and York). Regional samples are collected at an average density of one site per 2 square kilometres, urban sampling is at a density of 4 samples per square kilometre. Top soil samples are collected at a depth of 5 - 20cm. It is sieved through a 2mm mesh and milled to less than 150 microns. The data include analyses for some or all of the following elements by XRFS: Mg, P, K, Ca, Ti, Mn, Fe, V, Cr, Co, Ba, Ni, Cu, Zn, Ga, As, Se, Rb, Sr, Y, Zr, Nb, Mo, Pb, Bi, Th, U, Ag, Cd, Sn, Sb, Cs, La, Ce, Ge, Sc, Se, Br, Hf, Ta, W, Tl, Te and I. Loss on Ignition (LOI) and pH (in a slurry of 0.01 M CaCl2 ) is now routinely determined on 50% of regional and all urban samples.