The Geological Survey of Northern Ireland (GSNI) and the British Geological Survey (BGS)udhave completed geochemical surveys of Northern Ireland in three phases of sampling andudanalysis. Sampling and quality control were undertaken according to the G-BASE protocol ofudBGS, as follows:ud• Stream sediment and stream waters surveys in 1994-96 (2,908 sites in the west) and inud2004-06 (2,966 sites in the east). The sampling distribution averaged one site per 2.4 km2.ud• Soil sampling surveys of rural areas and of selected urban areas in 2004-06. 6,862 sitesudwere sampled at an average of one site per 2 km2. Two samples were collected at each site,udfrom depths of 5-20 cm and 35-50 cm.ud• Soil sampling of the urban areas of Belfast and Londonderry, at 1,315 sites at a distributionudof four sites per km2.udAnalyses were undertaken by laboratories (including BGS), selected by open tender, for a rangeudof inorganic compounds and trace elements, as follows:ud• Stream sediment and shallow soil samples were analysed by X-ray fluorescence (XRF)udspectrometry.ud• Shallow and deep soil samples were analysed by inductively coupled plasma (ICP)udspectrometry.ud• Deep soil samples were analysed for selected elements by fire-assay;ud• Stream water samples were analysed by ICP and ion-chromatography.udOne quarter of the urban soil samples (one site per km2) were analysed for a range of semivolatileudorganic carbons (SVOCs).udDigital databases and images of the results have been produced.
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