Radioactivity Levels in the Red Sea Coastal Environment of Sudan

摘要

Measurements of natural and fallout radionuclides in marine surface sediments, seagrass and algae collected from the Sudanese coastal waters of the Red Sea have been made using high resolution γ-spectrometry, radio-chemical separation and α-spectrometry. Activity levels of uranium isotopes, thorium isotopes, ~(226)Ra, ~(210)Po, ~(40)K and ~(137)Cs were determined in the samples. Comparison of the data on natural radionuclides from coastal marine sediments with those collected from 30 km offshore (Sanganeb atoll) reveals that both anthropogenic and terrestrial influx from the hinterland is negligible. However, values for ~(226)Ra and ~(210)Po are higher in the sediments of Port Sudan harbour relative to those from the adjacent fringing reefs. Uranium content is higher in shallow-water sediments and the authigenic fraction constitutes 12% on the average. The ~(228)Th: ~(232)Th disequilibrium in sediments indicates rapid rate of sedimentation at the sampling sites. The activity levels detected for ~(137)Cs in sediments collected from the Port Sudan harbour area are fairly high as compared with values from other sampling locations. On the basis of individual data, the variations are insignificant with regard to the uptake of natural radionuclides by marine species considered in this study. However, ~(137)Cs activity in algae ranged from 0.33 to 1.32 Bq kg~(-1) with Sargassum (brown algae) showing the highest level.