Terrestrial gamma radiation baseline mapping using ultra low density sampling methods.

Area of Science:

• Environmental Science
• Radiological Science
• Geochemistry

Background:

• Baseline terrestrial gamma radiation data is essential for incident assessment, epidemiological studies, and land remediation.
• Large-scale radiometric surveys are prohibitively expensive and impractical for vast areas like Queensland.

Purpose of the Study:

• To develop a cost-effective baseline terrestrial gamma radiation map for Queensland using existing geochemical data.
• To validate the use of ultra-low density soil sampling data for mapping terrestrial gamma radiation.

Main Methods:

• Utilized geoelement data from the National Geochemistry Survey of Australia (NGSA).
• Constructed a terrestrial gamma air kerma rate map delineated by major drainage catchments.
• Validated the methodology using in-situ measurements and soil sampling in selected catchments.

Main Results:

• A Queensland mean terrestrial air kerma rate of 49 ± 69 nGy h⁻¹ was calculated from NGSA data.
• Validation confirmed that catchment outlet measurements represent broader catchment radioactivity.
• NGSA geoelement data is suitable for calculating and mapping terrestrial air kerma rate.

Conclusions:

• An existing, ultra-low density geochemical sampling program can be effectively utilized to create baseline terrestrial gamma radiation maps.
• The proposed methodology offers a practical and economical approach for large-area radiation mapping.
• The derived background radiation range is suitable for generic terrestrial air kerma rate assessments.