Quality control of 2012 and 2013 southern England G-BASE stream water sample data

This report describes the quality control of the laboratory analyses of stream water samples collected in south west England during the summer of 2012 and some of those collected in 2013. The samples are part of the Geochemical Baseline Survey of the Environment (G-BASE) project. The analytical work was undertaken in the laboratories at the British Geological Survey (BGS) in Keyworth. The sample collection and field office methods followed the procedures described in Johnson (2005a), and with updates reported by Johnson (2005b). Stream water sampling methods were unchanged from 2010, the previous field season in which water samples were taken (Ander, 2014; Bearcock et al., 2016; Bearcock and Strutt, 2012). As the G-BASE project was due for completion by 2014 there were strict time and budget restraints. This meant that stream sediment samples taken by the BGS’s Mineral Reconnaissance Program (MRP) in the 1980s, and archived in BGS, could be reanalysed. Where MRP samples had been taken in close proximity to a planned G-BASE sample, only water samples were taken from that site. At all other sites stream sediments, panned concentrates, and water samples were collected as standard. Laboratory analysis for the 2013 samples was restricted due to financial constraints. The samples which were analysed are described more fully in Section 2.