Radioactivity levels in Lake Nasser sediments

Construction of the Aswan High Dam created one of the Worldʹs greatest man-made lakes, Lake Nasser, which is to be found in the most southerly part of Egypt. Concentrations of radionuclides in sediment and surface soil have been measured by both neutron activation analysis (NAA) and gamma spectrometry (GS). Concentrations (in Bq kg−1/dry wt) have been observed to range from 25 to 68 Bq kg−1 for 238U, 8.4–59.3 Bq kg−1 for 232Th, and from 16 ranges of concentration reported from lake sediments in other parts of the world. Comparison of the data obtained by NAA and GS indicates the possibility of a state of disequilibrium within the 238U series but not in the 232Th series.