The first comprehensive geochemical mapping in the UK was carried out by the Applied Geochemistry Research Group at Imperial College London.
This remains the only completed high density regional geochemical stream sediment survey of England.
A rapid field sampling programme, carried out in the space of just one year (1969), collected stream sediments from 49 464 sites in England and Wales giving an approximate sampling density of one sample every three square kilometres.
However, this density does not account for the unsampled urban areas and regions of no surface drainage (e.g. over chalk). The results are presented as interpolated geochemical images in the Wolfson Geochemical Atlas of England and Wales (Webb et al., 1978).
At each drainage site, composite samples were collected from a stretch of the active drainage channel at least 20 m upstream from the road used to access the stream.
Samples were dried at 60–80ºC . After disaggregation the sample was sieved to minus 80-mesh (c. 200 µm).
The majority of elements were determined by direct current optical emission spectrometry (DCOES) (Al, Ba, Co, Cr, Cu, Fe, Ga, Li, Mg, Mn, Ni, Pb, Sc, Si, Sr, Ti and V.
The following elements were also determined but rejected on the basis of poor quality: Ag, Bi, Be, La, Zr and W).
Zinc and Cd were determined by atomic adsorption spectrophotometry (AAS). Following a nitric acid extraction, Mo and As were determined colorimetrically after a potassium hydrogen sulphate fusion.
Enquiries about the geochemical data should be directed to Imperial College London.
Webb, J S, Thornton, I, Thompson, M, Howarth, R J, and Lowenstein, P L. 1978. The Wolfson geochemical atlas of England and Wales. Clarendon Press, Oxford.