Airborne radiometric data: in search of the lost peatlands, Anglesey, North Wales

Soil carbon plays a crucial role in maintaining soil health, regulating water retention, and overall ecosystem function, while also acting as a carbon sink that can mitigate climate change. Updating peat information has become a priority in relation to carbon accounting. Soils attenuate radiometric flux by virtue of their bulk density and water saturation. The largest contrasts are associated with high carbon, wet peat zones. A revised attenuation theory demonstrates the response continuum of all soils and defines their response over the full range of saturation levels. The theory can be applied to any form of radiometric survey data. The relevance of the attenuation properties of airborne radiometric data to peat mapping is well established. Mainly due to survey height, the spatial resolution of the radiometric data is limited. It has been argued that conventional peat mapping has omitted many potential areas of peat, often excluded on the basis of depth. These smaller pockets of the carbon store have been termed the lost peatlands. A new observational and adaptable assessment of the peat extent across Wales has recently been published. An existing small airborne survey is used to provide an attenuation assessment of peat extents in relation to the control provided by the new map. Many of the peat zones are small (<0.05 km²) and are detected on only one or two flightlines. The large support volume (footprint) of airborne measurements provides a moving-average of subsurface contributions. Despite this, the attenuation response appears sufficient to either confirm or reject the evidence of a peat zone. The data also suggest many other areas of potential peat.