摘要：In an attempt to understand the geochemical behaviour of 238U, 232Th, 40K and the fallout nuclide 137Cs in aquaticsediments, surface sediments were collected from White, Blue and River Nile and fractionated into seven grain sizes(2000-1000, 1000-500, 500-250, 250-200, 200-125, 125-100 and < 100 μm) and analysed for the said elementsusing high-resolution gamma-spectrometry. Activity concentration of 238U, 232Th and 40K in the bulk samples displaysimilar values in the three rivers. Results revealed clear inverse relationship between activity concentration and grainsize in White and Blue Nile, while the trend is not clear in the River Nile. Activity concentrations of the respectiveradionuclides in different grain sizes indicated that White Nile sediments are more homogenous with respect to particlesize as compared to Blue and River Nile. The activity concentration of the fallout radionuclide 137Cs in the bulksamples found to be ten times lower in the White Nile sediments (0.28±0.33) Bq kg−1 as compared to Blue Nilesediments (2.92±0.77) Bq kg−1.
关键词：Radioactivity ; Geochemistry ; River Nile ; Aquatic sediments ; Grain size
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