Environmental and mineralogical studies on the stream sediments of Baltim-El Burullus coastal plain, North Delta, Egypt.

This work is mainly concerned with the effect of anthropogenic activities and natural radioactivity due to the presence of highly radioactive black sand spots, factory construction, and shipping, in addition to other activities like agriculture on human beings. Forty samples were collected along Baltim-El Burullus coastal plain to detect the effect of these problems and determine the suggested solutions. The black sand of the Baltim-El Burullus coastal plain exhibits a considerable amount of economically heavy minerals, their ratio relative to the bulk composition in the investigated samples ranges from 3.18 to 10.5% with an average of 5.45%. The most important of them are magnetite, ilmenite, rutile, leucoxene, garnet, zircon and monazite. The existence of some radioactive-bearing accessory mineral deposits like zircon and monazite led to measuring the naturally occurring radionuclides 226 Ra, 232 Th and 40 K to evaluate the excess lifetime cancer risk (ELCR). The results showed that these concentrations are 19.1 ± 9.73, 14.7 ± 9.53 and 211 ± 71.34 Bq kg-1 were lower than the corresponding reported worldwide average of 35, 45, and 412 Bq kg-1 for each radionuclide (226 Ra, 232 Th, and 40  K). The gamma hazard indices such as absorbed dose rate (Dair ), the annual effective dose (AED), and excess lifetime cancer risk (ELCR) factor were computed in the investigated sediments and all the results were found (Dair  = 26.4 nGy h-1 , AED = 0.03 mSv year-1 , ELCR = 0.0001) to be lower than the values suggested by the United Nations Scientific Committee on the effect of Atomic Research (59 nGy h-1 , 0.07 mSv year-1 and 0.0029 for Dair , AED and ELCR, respectively). The study suggests that the black sand is safe to use in various infrastructure applications at Baltim-El Burullus coastal plain. The levels of radioactivity are not high enough to pose a risk to human health.