NATURAL RADIOACTIVITY STUDIES OF PHOSPHATE FERTILIZERS APPLIED ON GREEK FARM SOILS USED FOR WHEAT CULTIVATION

Area of Science:

• Environmental Science
• Radiation Protection
• Agricultural Science

Background:

• Naturally Occurring Radionuclide Materials (NORM) are present in various environmental components, including agricultural inputs and products.
• Understanding the radiation hazard associated with NORM is crucial for public and occupational safety.

Purpose of the Study:

• To assess the radiation hazard from NORM in fertilizers, agricultural soils, and wheat grain.
• To evaluate the radioprotection needs for workers involved in fertilizer handling and transportation.

Main Methods:

• Activity of key radionuclides (238U, 226Ra, 232Th, 40K) was measured using gamma spectrometry.
• Hermetical sealing of samples prevented radon (222Rn) escape, ensuring accurate measurements.
• External dose rates were calculated for different occupational scenarios.

Main Results:

• Phosphate fertilization did not significantly alter the natural radioactivity of soils or wheat grain.
• Fertilizers exhibited a higher mean dose rate (211 nGy h-1) compared to fertilized soils (53 nGy h-1).
• Maximum external dose rates for truck drivers (1.15 mSv y-1) approached the annual effective dose limit, while fertilizer storage workers faced higher risks (up to 1.98 mSv y-1).

Conclusions:

• While soil and crop radioactivity remained unaffected by fertilization, fertilizers themselves represent a significant source of radiation exposure.
• Radioprotection measures are essential for workers handling fertilizers, particularly in storage and supply roles, due to elevated dose rates.