RESUMO
Sediment and seafood samples were collected from Makoko Lagoon, Lagos state, Nigeria. Gamma-ray spectrometry was used to determine the activity concentrations of 40K, 226Ra and 232Th in the samples. The average activity concentrations of 40K, 226Ra and 232Th in the sediment were 41.04 ± 6.41, 10.15 ± 3.19 and 4.39 ± 2.10 Bq kg-1, respectively, while the annual effective dose was 0.01 mSv/year. In seafood, the average activity concentrations of 40K, 226Ra and 232Th were 15.66 ± 8.07, 1.72 ± 1.51 and 1.93 ± 0.30 Bq kg-1, respectively. The cumulative effective ingestion dose obtained ranged from 0.016 µSv/year (giant prawn) to 1.08 µSv/year (Parrotgrunt). The mean activity concentrations and absorbed dose rate in sediment were below the worldwide average values. The cumulative dose from the ingestion of seafood was also significantly low. Sediment and seafood from the lagoon in Makoko pose no health risk from a radiological point of view to the population.
