Mapping potassium and thorium concentrations in Belgian soils

Area of Science:

• Geosciences
• Environmental Science
• Radiological Science

Background:

• The European Atlas of Natural Radiation provides maps of natural radionuclides like potassium (K) and thorium (Th).
• Belgium offers a unique case study for mapping these radionuclides due to diverse available datasets, including airborne survey data.
• Existing datasets require calibration and harmonization for accurate radiological mapping.

Purpose of the Study:

• To explore and validate methodologies for mapping natural radionuclides (K and Th) in Belgium.
• To calibrate airborne survey data using harmonized soil and geochemical data.
• To assess the effectiveness of different spatial interpolation and data smoothing techniques.

Main Methods:

• Harmonization of potassium and thorium soil data from radiological and geochemical sources.
• Calibration of airborne survey data using the harmonized soil database.
• Application of spatial interpolation and smoothing techniques, including moving average (MA) with and without constraints (soil class, geological unit).

Main Results:

• Reasonable agreement was found between maps generated from airborne and harmonized soil data across various interpolation methods on a 1x1 km² grid.
• Map agreement improved significantly when data was aggregated to a 10x10 km² grid, aligning with the European Atlas resolution.
• The moving average method constrained by geological unit yielded the best agreement between the datasets.

Conclusions:

• Calibrating airborne radiation data with harmonized soil data is a viable method for improving natural radionuclide maps.
• Spatial interpolation, particularly when constrained by geological units, effectively reconciles different data sources.
• The findings support the methodology used in the European Atlas of Natural Radiation and highlight potential improvements for regional radiological mapping.