Radioactivity concentrations of 40K, 134Cs, 137Cs, 90Sr, 241Am, 238Pu and 239+240Pu radionuclides in Jordanian soil samples

Abstract

In November 2000, surface and core soil samples were collected from different regions of Jordan. The samples were analyzed by direct gamma spectrometry and combined radiochemical separation procedure to quantify 40K, 134Cs, 137Cs, 90Sr, 241Am, 238Pu and 239+240Pu radioactivity. Concentrations (Bq.kg -1 dry weight) have been observed to vary in the range 1.5–2.6 for 134Cs, 2.8–11.4 for 90Sr, and 0.13–0.48 for 241Am, 0.016–0.062 for 238Pu, 0.28–1.01 for 239+240Pu and 155–543 for 40K. The typical concentration of 137Cs found in topsoils (0–2 cm) ranged in 7.5–576 Bq.kg −1, dry weight. These values were greater than those observed in samples taken at greater depths (up to 32 cm). Activity ratios of 134Cs/ 137Cs, 90Sr/ 137Cs, 239+240Pu/ 137Cs, 238Pu/ 137Cs, 241Am/ 137Cs, 239+240Pu/ 238Pu and 241Am / 238Pu have mean values of 0.0049 (R=1), 0.29 (R=0.76), 0.41 (R=0.90), 0.39 (R=0.85), 0.41 (R=0.88), 7.72 (R=0.97) and 16.66 (R=0.98), respectively. The underlying concentrations were correlated and relatively higher than those reported in neighboring countries. One moss sample, as a biomonitor indicator, was measured and evaluated along with the soil samples. Its data showed higher concentrations of all measured radionuclides due to accumulations over years. The depth distribution of the fission product 137Cs and the total deposition (Bq.m −2) were also studied in selected samples. Estimations of the annual effective dose equivalent due to 137Cs-soil contamination showed values up to more than 200 μSv.