Radiological Study and Transfer Behavior (Soil-to-Plant) for Some Radionuclides

Abstract

This study aimed at perfonning a detailed analysis, estimation and evaluation of both natural and anthropogenic radioactivity levels in El- • Behera governorate. It is located in the northwestern section of the Egyptian Delta. This region was chosen due to, its economic and agricultural importance, and richness in natural resources.

This study was conducted using different analytical techniques (gamma spectrometry, alpha particle spectrometry and gross alpha beta techniques) to assess radionuclide concentrations from both the natural and anthropogenic origin in the collected soil and plant (clover) samples.

Regarding soil samples analyzed using gamma spectrometry, it was noticed that the average specific activities for the naturally occurring

radionuclides 238

2 ) 232Th and

4'1<. were 19.8, 22.3 and 359.4

Ue 1 Bq.kg" , respectively. These results are within the worldwide average, which are 35, 35 and 370 Bq.kg-1 for 238Ue26Ra), 232Th and 4°K, respectively (UNSCEAR, 1993). The maximum specific activity for the anthropogenic radionuclide 137Cs,which is from global fall-out of the old nuclear weapons testing during the earlf fifties and sixties and nuclea; accidents, was found to be 13.9 Bq.kg•. The highest values of cesiuni were found toward north. This was explained by the fact that the northerd section of the study area receives a relatively higher rainfall.

. The isotopic analysis of uranium for soil samples via alpha spectrometry showed average specific activities of 21.9, 0.92 and 21.B Bq.kg-1 for 234U, 235U and 23SU respectively. The average ratio of t e 238 26Ra) using gamma spectrometry (238Uy) to those obtained by alpHa

spectrometry (238

) was 0.96 (many of the 238UyF38

activity ratiJs

were approximately equal to one). A fair positive correlation was fourld between the uranium concentrations obtained using alpha spectrometry to those obtained using gamma spectrometry. These data indicate the goJd accuracy of gamma spectrometry measurements for 238U in soils using its I series progenies. In addition, the data suggest the existence of secular equilibrium between the 238U and its series members in the soil samplbs. Also, this indicated that the soil samples were homogeneous, since the used mass of soil samples are 2 gm for alpha spectrometry while they ire 100 gm for gamma spectrometry.