Analysis of activity concentrations due to natural radionuclides in the fish of Kainji Lake

A study was conducted for natural radioactivity of some fish samples from Kainji Lake, situated between latitudes 9~' 50' - 10~' 57' North and longitudes 4~'25'-4~'45' East, New Bussa, Niger state, Nigeria, using gamma spectroscopy method with Nal(TI) detector. Radioactivity a phenomenon that leads to production of radiations, and radiation is known to trigger or induce cancer. The fish are analyzed to estimate the radioactivity (activity) concentrations due to natural radionuclides (Radium 222(226Ra), Thorium 232(232Th) and Potassium 40 (40K). The obtained result shows that the activity concentration for (226Ra), in all the fish samples collected ranges from 16.06 ~c 0.44 Bqkg-1 to 67.39 ~c 12.34 Bqkg-1 with an average value of 37.22 ~c 4.31 Bqkg-1. That of 232Th, ranges from 42.66 ~c 0.81 Bqkg-1 to 200.6 ~c 10.66 Bqkg-1 and the average value stands at 94.82 ~c 3.82 Bqkg-1. The activity concentration for 40K, ranges between 243.3 ~c 1.56 Bqkg-1 to 384.98 ~c 11.97 Bqkg-1 and the average is 618.2 ~c 26.81 Bqkg-1. This indicated that average daily intake due to natural activity from the fish is valued at 0.999 Bq/day, 2.545Bq/day and 10.31 Bq/day for 226Ra, 232Th and 40K respectively. This shows a promising result, since the activity concentration values for most of the fish are within the acceptable limits. However location Upstream02 (9~'51'.285~AN, 4~'35'.533~AE) and Upstream07 (9~'51'.285~AN, 4~'35'.533~AE) fish, became outliers with significant values of 1 13.10~kSvy-1 and 121.68~kSvy-1 effective dose. This could be attributed to variation in geological formations in the lake as well as the feeding habits of these fish. The work shows that consumers of fish from Kainji Lake have no risk of radioactivity ingestion, even though no amount of radiation is assumed to be totally safe.

Includes: 16 references.