In Situ Determination of Radioactivity Levels and Annual Effective Dose Rate from Soil Samples around the Gosa Dumpsite in FCT, Abuja

Open dumpsites represent a potentially significant source of elevated ambient gamma radiation in peri-urban environments due to the heterogeneous composition of municipal solid waste deposited at such facilities. This study presents in situ measurements of ambient gamma dose rates, annual absorbed doses (AD), and annual effective doses (AED) in soils at the Gosa dumpsite, Federal Capital Territory (FCT), Abuja, Nigeria. Measurements were conducted at six dumpsite soil points (PT1–PT6) and one background control soil site using two independently calibrated radiation survey meters — the RADEYE G20-10 and the RADOS RDS-120. The mean dose rate (MDR) across the dumpsite ranged from 0.11 to 0.17 µSv/h (mean 0.13 ± 0.02 µSv/h), corresponding to absorbed dose rates of 110–170 nGy/h. The annual effective doses ranged from 0.1349 to 0.2085 mSv/y (mean 0.1533 ± 0.0245 mSv/y). The background control soil site recorded a dose rate of 0.06 µSv/h and an AED of 0.0736 mSv/y. Percentage errors between the two instruments ranged from 0.00% to 42.86% (mean 18.53%), consistent with expected Geiger-Müller instrument variability in heterogeneous field conditions. All measured annual effective doses remained well below the 1 mSv/y public dose limit recommended by the International Commission on Radiological Protection (ICRP). These results constitute the first baseline radiological dataset for the Gosa dumpsite and underscore the need for periodic monitoring and improved solid waste governance in the FCT.