Study of soil-fern transfer of naturally occurring alpha emitting radionuclides in the Southern Region of Cameroon.

This study was carried out in the localities Melondo and Ngombas located in the Southern Region of Cameroon where there are known to be uranium-bearing and high background radiation areas. Activity concentrations of naturally occurring radionuclides Po, U, U, U, Th, Th, Th and Ra were determined in soil and fern (filicophyta) samples collected at 10 points in both localities. In soil, the average values of these activity concentrations (in Bq.kg d.w.) were Po(130 ± 10), U(126 ± 11.6), U(5 ± 1), (131 ± 10), Th(400 ± 22), Th(145 ± 11), Th(381 ± 21) and Ra(154 ± 28) at Melondo; and Po(228 ± 1), U(170 ± 11), U(9 ± 2), U(179 ± 12), Th(200 ± 18), Th(184 ± 18), Th(228 ± 22) and Ra(416 ± 7) at Ngomba. In fern the average activity concentrations were: Po(35 ± 3), U(0.68 ± 0.05), U(0.042 ± 0.01), U(0.90 ± 0.05), Th(1.2 ± 0.2), Th(0.7 ± 0.1), Th(39 ± 3) and Ra(14 ± 3) at Melondo and Po(24 ± 2), U(0.82 ± 0.06), U(0.046 ± 0.01), U(0.92 ± 0.06), Th(0.8 ± 0.2), Th(0.9 ± 0.2), Th(15 ± 5) and Ra(14 ± 3) at Ngomba. The soil-fern transfer factors (TF) (in kg.kg) were respectively Po(1.64 × 10), U (5 × 10), U(7 × 10), U(6 × 10), Th(3 × 10), Th(5 × 10), Th(7.9 × 10), and Ra(5.1 × 10). The highest TF for fern was for Po, probably because of atmospheric deposition. The TFs of uranium and thorium were comparable to those given in the IAEA handbook for grass.