This dataset has now been superseded, please see the Estimated Ambient Background Soil Chemistry England and Wales dataset. This dataset indicates the estimated topsoil Arsenic(As), Cadmium (Cd), Cr (Chromium), Nickel (Ni) and Lead (Pb) concentrations (mg kg-1) derived by spatial interpolation of the point source urban soil PHE (potentially harmful elements) data. Urban soil geochemical data generally have large positive skewness coefficients so were transformed by taking natural logarithms. To overcome the bias associated with traditional measures of location (mean) and scale (standard deviation) for log-normal data, the inverse distance weighted (IDW) mean and standard deviation of log transformed element concentrations were used for mapping the spatial variation in As, Cd, Cr, Ni and Pb concentrations. The soil chemistry data is based on GBASE (Geochemical Baseline Survey of the Environment) soil geochemical data where these are available. Elsewhere the stream sediment data are converted to surface soil equivalent potentially harmful element(PHE) concentrations. This dataset covers England and Wales but data is available for the whole of Great Britain, with the exception of the London area where an inadequate number of geochemical samples are available at the moment.
