Normal background concentrations of contaminants in the soils of England : available data and data exploration

This draft report describes the completed Work Package 1 and 2 tasks of the Defra commissioned Science and Research Project SP1008 - Establishing data on normal/background levels of soil contamination in England. Work Package 1 (WP1) has investigated the available soil data sets that can be used to determine the Normal Background Concentrations (NBCs) for contaminants in soils from England. A database of available data set information has been created investigating the sample coverage, the sampling strategy and methods, the laboratory procedures, and the robustness, format and availability of the data. Key data sets are the British Geological Survey’s G-BASE topsoils for urban and rural areas and the National Soil Inventory (XRFS reanalysed) data which, although at a reduced sampling density compared to G-BASE, has complete coverage for both England and Wales. Supplementary minor data sets are also included in the Project’s extensive bibliographic database. There are also large data sets available that specifically target a particular land use or activity, i.e. not systematically collected, e.g. the BGS Mineral Reconnaissance Programme (MRP) soils. Such data will not be used to estimate NBCs as they will cause a substantial bias in the determinations. This data and information gathering phase will underpin subsequent work packages of this project. Work Package 1 has also addressed some key questions such as, “what are the priority contaminants?” and “what is meant by a normal background concentration?”