The status of natural radioactivity and heavy metals pollution on soil at Assiut Zone in Central Upper-Egypt

Abstract

Context: To examine the status of the environmental quality of the soils in Assiut zone in central Upper-Egypt, investigation was carried out to determine the concentration of natural radionuclides (radium [ 226 Ra], thorium [ 232 Th] and 40 K) and the contents of eight heavy metals (Cd, Pb, Ni, Fe, Mn, Cr, Cu, and Zn). Materials and Methods: The measurements of concentration of natural radionuclides were carried out by using the gamma spectrometry (NaI (Tl); 3× 3). Results: The results indicate that the soil samples' radioactivity concentrations of 226 Ra, 232 Th, and 40 K were ranging from 10.4 ± 0.5 to 19 ± 1 Bq/kg; 6 ± 0.3-21 ± 3 Bq/kg and 103.6 ± 5-221 ± 10 Bq/kg respectively. The typical radiation doses (D o ), the external hazard index (H ex ) and annual effective dose rate values for the corresponding samples were also estimated. The concentration of heavy metals was measured by using the atomic absorption spectrometry method. Data were analyzed by using the statistical methods. The representative H ex values for the corresponding samples were also estimated. Generally, heavy metals and major elements concentration of the sediments were found decrease in sequence of Fe > Mg > pb > Zn > Cr > Cu > Ni > Cd. In some locations, the concentration for the investigated heavy metals exceeds the permissible limits recommended by the Canadian Environmental Quality Guidelines. The highest concentration of the most heavy metals (Cd, Pb, Ni, Cr, and Zn) was found in Arab Al-Madabegh region; the sewage irrigated zone. Whereas, the lowest ones was found in the not irrigated lands, which considered as a reference point of analyses. Conclusion: The maximum admitted concentrations of toxic heavy elements in the sensitive areas revealed to be exceed from three to thirty times than the non-irrigated zone.