Previous measurements of environmental radioactivity have been focused mainly on impacts on humans. However, in recent years, increased emphasis has been placed on assessing the radioactive impact on non-human biota. This is in recognition that human protection may be insufficient to assure environmental protection. The necessity to safeguard non-human biota against ionizing radiation prompted the development of a variety of models and methodologies (such as RESRADBIOTA, ERICA tool, DosDiMEco, LIETDOS-BIO) for dose and risk assessments. In this study, the ERICA model has been adopted to determine the dose to non-human biota for the first time at the El Amin University proposed site in Minna, North central Nigeria. The initial radiological assessments of the soil in the area have revealed potential dose risk to humans, with maximum specific activities of 152.60 and 185.9 Bq/kg for Ra-226 and Th-232 respectively. These activities were used as input data in the ERICA model, in order to ensure that maximum possible value of dose rates to non-human biota was below the screening dose rate criterion of 10 μGy/h. Dose rates to non-human terrestrial biota computed, varied from 0.29 μGy/h (for tree) to 16.69 μGy/h (for lichen and bryophytes), while the dose rates for non-human aquatic biota varied from 0.002 μGy/h (for mammal) to 36.329 μGy/h (zooplankton). The results obtained could serve as a baseline data for the assessment of possible anthropogenic enhancement of the total dose rate to non-human biota of the study area.
Keywords: Environmental radioactivity; Gamma dose rates; Ionizing radiation; ERICA dose assessment tool; Maximum specific activity