Black sand deposits; their spatial distribution and hazards along the northern coast of Sinai Peninsula, Egypt

Abstract

Airborne Gamma Ray Spectrometric (AGRS) surveys and image processing techniques are utilized to define the occurrence of black sand deposits along Sinai's northern coastal plain. High contents of radioactive minerals are detected in these deposits; zones of high concentrations of uranium 238U, thorium 232Th, and potassium 40K could be outlined. Remote sensing and GIS techniques are integrated to study the pattern of coastline changes and its relationship to the distribution of black sand deposits during the period between 2000 and 2020. The results reveal high 232Th anomalies along El-Arish Beach due to its high monazite content; containing 7.92% ThO2. In addition, high uranium anomalies on the eastern sides of El-Bardawil Lake result from the abundance of zircon in the sediments surrounding the lake, which contain 5.29% U3O8. Areas of high radiation levels, which exceed the allowed limits for human exposure, are outlined by calculating adsorbed and annual effective dose rates. Unfortunately, many of these areas are open and easily accessible to the public, presenting a direct threat to the health of local inhabitants. These anomalous areas ought to be excluded from the ongoing national housing and land reclamation projects, where long-term exposure to high gamma radiation increases the cancer risk factor in humans.