Natural radioactivity levels in benthic foraminifera Sorites marginalis as a pollution indicator

Sorites marginalis as one of the benthic foraminifer's genera were collected from three coastal lagoons (Abu Shaar, Umm al-Huwaytāt, and Marsa Shūni) on the Egyptian Red Sea coast and investigated for their ²²⁶Ra, ²³²Th, and ⁴⁰K content using HPGe gamma-ray spectrometry. S. marginalis shells show high radioactivity levels with average activity concentration values of 251.8 ± 18.3, 86.8 ± 7.7, and 791.2 ± 57.6 Bq kg^-1, 327.1 ± 11.4, 97.4 ± 7.1, and 751.6 ± 54.7 Bq kg^-1, 246.6 ± 17.7, 65.1 ± 4.8, and 477.6 ± 34.8 Bq kg^-1 for ²²⁶Ra, ²³²Th, and ⁴⁰K in the samples from Abu Shaar, Umm al-Huwaytāt, and Marsa Shūni, respectively. ²²⁶Ra and ⁴⁰K have a high tendency to accumulate in S. marginalis compared to ²³²Th. High bioaccumulation of the studied radionuclides was found for samples from Umm al-Huwaytāt and Abu Shaar lagoons. Radiological parameters such as radium equivalent activity, gamma absorbed dose rate in air, and outdoor annual effective dose were calculated, and values higher than the permissible limits were obtained. Based on the obtained results, the estimation of radioactivity levels in S. marginalis shells may serve as an indicator of marine environment pollution.