This layer displays the urban areas for which there is an "urban geochemical mapping" report. An integral part of the G-BASE (Geochemical Baseline Survey of the Environment) mapping programme is to map and establish the soil geochemical baselines of urban areas. These data provide unique soil chemical information for the urban environment and are used to; assess the condition of soils within populated areas, identify and quantify human impact on soils in urban areas through comparison with the rural, natural soil geochemical background and Indicate elevated concentrations of potential harmful elements. 27 urban areas which have been sampled by the project to date.These include Glasgow, Nottingham, Ipswich and Cardiff.

This layer of the map based index (GeoIndex) shows the boundaries of the G-BASE (Geochemical Baseline Survey of the Environment) project mapping areas which are reported as geochemical atlases. The majority of atlases are for stream sediments, with data on stream waters and soils included when available. Separate stream sediment, soil and stream water atlases have been published for Wales. Wales and north of Humber-Trent are reported as hardcopy generally A3 sized publications. The Humber-Trent atlas is available as a pdf file on a CD-ROM. Atlases are available for Shetland, Orkney, South Orkney and Caithness, Sutherland, Hebrides, Great Glen, East Grampians, Argyll, Southern Scotland, Lake District, NE England, NW England and N Wales, Humber-Trent, Wales and West Midlands. Atlases are not available yet for the East Midlands, East Anglia, SE England and SW England.

The map shows the location of excess sample materials from the G-BASE (Geochemical Baseline Survey Of The Environment) geochemistry project:- stream sediments, panned heavy mineral concentrates and soils are stored long term in the National Geoscience Data Centre and are available for use in other projects. The Minerals Programme (incorporating the Mineral Reconnaissance Programme) sample collection contains reference samples of drill cores, rocks, tills, soils, stream sediments and panned concentrates. These samples were collected in the period 1974 - to date in mineralised and potentially mineralised areas of the United Kingdom, principally in the northern and western Britain.

The BGS has been commissioned by Defra to provide guidance on what are 'normal' levels of contaminant concentrations in English soils in support of the revision of the Part 2A Contaminated Land Statutory Guidance. The domain polygons and other data produced by this work are served as WMS here.

This layer of the map based index (GeoIndex) shows the locations where stream sediment samples are collected under the G-BASE (Geochemical Baseline Survey of the Environment) programme at an average density of approximately one site per 1.5 km square. Analytical data for the minus 150 micron fraction of stream sediment samples are available for some or all of the following elements by a variety of analytical methods (now predominantly 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. Stream sediment samples were also collected by the now defunct MRP programme and analytical data for the minus 150 micron fraction of samples is available for a variety of elements including Ag, As, Au, Ba, Bi, Ca, Ce, Cu, Fe, Mn, Mo, Ni, Pb, Sb, Sn, Sr, Ti, U, V, W, Zn and Zr. Some of the MRP samples may have undergone several stages of analysis, some for inclusion in the G-BASE project. The samples may have been assigned a different sample number but will plot at the same site. Data is available for most Great Britain, apart from some parts of Southern England which have yet to be surveyed.

Profile soil analyses are available from a number of BGS programmes, notably the Mineral Reconnaissance Programme (MRP) and the Geochemical Baseline Survey of the Environment (G-BASE) programme. Sampling depth and range of analytes determined is very variable for the MRP. G-BASE samples are consistently from 35 - 50 cm though since 2003 it has become routine practice in the G-BASE project to collect a top soil and deeper profile sample from the same site but only analyses the top soil and store the profile soil. This also applies in urban areas. The G-BASE profile soils were generally sieved to 150 microns before analysis and determined by XRFS for some or all of: 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. MRP samples can include profile samples from greater than 1 meter collected using a power auger and also include till samples. The G-BASE samples are collected at a density of 1 sample per two square kilometres in rural areas and 4 samples every kilometre square in urban areas. MRP sampling was more site specific generally collecting soil samples along lines at spacing intervals generally 25 - 250 m.

Data from the British Geological Survey's GeoIndex Geochemistry theme are made available for viewing here. GeoIndex is a website that allows users to search for information about BGS data collections covering the UK and other areas world wide. Access is free, the interface is easy to use, and it has been developed to enable users to check coverage of different types of data and find out some background information about the data. More detailed information can be obtained by further enquiry via the web site: www.bgs.ac.uk/geoindex.

Water samples have predominantly been collected by the G-BASE (Geochemical Baseline Survey of the Environment) project at an average sampling density of one sample per 1.5 km square. Samples have been collected from approximately 85% of Great Britain but it is only from Wales and Humber-Trent southwards that a wide range of analytes have been determined. Currently G-BASE stream water samples collected from high order streams are determined by ICP-AES for 27 elements - Sr, Cd, Ba, Si, Mn, Fe, P, S (as SO42-), B, Mg, V, Na, Mo, Al, Be, Ca, Zn, Cu, Pb, Li, Zr, Co, Ni, Y, La, K and Cr; and by quadrupole ICP-MS for 24 trace elements - Li, Be, Al, V, Cr, Co, Ni, Cu, As, Rb, Y, Zr, Mo, Ag, Cd, Sn, Sb, Ba, La, Ce, Tl, Pb, Th and U. Automated colorimetric methods are used to determine Cl and NO3- and ion selective electrode is used to determine F. Waters are also analysed for non-purgeable organic carbon (NPOC) to determine dissolved organic carbon content. All samples have routinely been analysed for pH, conductivity and bicarbonate. Much of the UK coverage also includes uranium and fluoride analyses.

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.