Modelling seasonal variations of natural radionuclides in agricultural soils

G Buttafuoco,I Guagliardi,R De Rosa,R Froio,N Ricca,A L Gabriele,Nicola Pirrone,D Civitelli,M G Cipriani

doi:10.1051/e3sconf/20130108009

Abstract

Estimating activity of natural radionuclides in agricultural soil is very important for the protection of public health because the released radioactivity can enter the food chain. Radioactivity measurements were carried out in two different dates (winter and summer) in agricultural soil using a GRM-260 gamma-ray spectrometer. The study area (100 m x 100 m) was an olive orchard in southern Italy. Measurements were carried out at 361 locations in January and July 2011. At the same locations, soil water content was measured to take into account the effect of soil moisture on radioactivity. A multi-Gaussian approach was used to explore and map the activity of naturally occurring radionuclides and soil water content for both seasons of measurements. The minimum radioactivity values were recorded in winter and the maximum values in summer, probably as a consequence of changes in weather and soil conditions (rainfall, soil moisture, temperature).

Highlights

Radioactivity is omnipresent in the earth’s crust in different amounts for both natural and man-made origin (Akhtar et al, 2005)
Estimating activity of natural radionuclides in agricultural soil is very important for the protection of public health because the released radioactivity can enter the food chain
Gamma-ray measurements and soil water content can be regarded as regionalized variables (Matheron, 1971) and values at unsampled locations were predicted using the geostatistical methods

Summary

Introduction

Radioactivity is omnipresent in the earth’s crust in different amounts for both natural and man-made origin (Akhtar et al, 2005). Soil on the earth’s crust is a source of radioactive risk, for continuous exposure to human being, and, in case of agricultural soil, for the entry of radionuclides into the food chain and into humans through the crops. At this regard soil-to-plant transfer constitutes one of the key processes, since in the long term the entry of radioelements into human food chains is controlled by the uptake of plant roots. These characteristics produce an evident seasonality in radionuclides caused by the sharp contrasts in temperature and relative humidity (Baeza et al, 2001)

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