Trial airborne EM surveys to assess minewater pollution in the UK

Drainage from mining operations is one of the most significant causes of freshwater pollution in some regions of the UK. Airborne electromagnetic (EM) surveys can map the distribution of subsurface resistivity in a continuous manner and can, under favourable circumstances, track concentrations of anomalous pore fluids. This paper presents trial high resolution EM data collected across the Nottinghamshire coalfield. High conductivities are associated with a sequence of colliery spoil zones and the conductive zones appear to extend both vertically and laterally away from the source material. Near-surface conductivities are enhanced by a factor of >10 above regional values. The airborne information provides spatial continuity which is important when dealing with environmental problems involving flow. The data await additional ground-based information to establish the nature of the links between subsurface geochemisty and the geophysical responses observed.