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Around 200 words, intelligible without reference to the text or references Geochemical and related studies have been made of near surface sediments from the Clyde estuary and adjoining areas, extending from Glasgow to the north and west as far as the Holy Loch. Multibeam echosounder, sidescan sonar and shallow seismic data, taken with core information indicate a shallow layer of modern sediment, often less than a metre thick, rests on earlier glacial and post-glacial sediments. The offshore Quaternary history can be aligned with onshore sequences with recognition of buried drumlins, settlement of muds from quieter water probably behind an icedam and later tidal delta deposits. The geochemistry of contaminants within the cores also indicates shallow contaminated sediments often resting on pristine pre-industrial deposits at depths less than 1 m. The distribution of different contaminants with depth in the sediment, such as Pb (and Pb isotopes), organics and radionuclides allow chronologies of contamination from different sources to be suggested. Dating was also attempted using microfossils, radiocarbon and 210 Pb but with limited success. Some of the spatial distribution of contaminants in the surface sediments can be related to grain size effects. Contaminants are highest, both in absolute terms and in enrichment relative to the natural background, in the urban and inner estuary and in the Holy Loch reflecting the concentration of industrial activity.

Using the Tellus and Tellus Border geochemistry data, the distribution of metals in topsoils in and around Derry-Londonderry has been mapped and assessed. The concentrations of metals have been compared with the UK Environment Agency's Soil Guideline Values (SGVs). Of 763 samples analysed, only 11 samples exceed the SGV for arsenic and two for that of cadmium. Of these 13 sites, only two were within an urban area. Concentrations of metal in the rural sub-catchments appear to be mainly determined by the underlying geology.Using a geographic information system (GIS) and multi-element plots (spidergrams) for analysis, the geological background was modelled at a sub-catchment scale in order to determine whether high soil metal concentrations were of natural origin or a consequence of anthropogenic activities. The level of enrichment due to contamination was calculated for 12 metals and metalloids. In the urban area of Derry-Londonderry, levels of arsenic, cadmium and seven other elements are slightly enhanced due to anthropogenic activities. However, as the enrichment factors do not exceed a factor of 3 these enhancements are classified as minor. Possible modern and historic sources of contamination are likely to be buildings, households and waste disposal, hospitals and medical facilities, surface run-off from road traffic, manufacturing industries, coal disposal and sewage works. How to cite this chapter: Lass-Evans, S., 2016 'Mapping metallic contamination of soils in the Lower Foyle catchment' in M.E. Young (ed.), Unearthed: impacts of the Tellus surveys of the north of Ireland. Dublin. Royal Irish Academy.