| dc.description.abstract | This study was initially formulated specifically to provide data of radioactivity and
elemental content of soils from two regions; Nguluku and Maumba, in Kwale District,
that are earmarked for Titanium mining project. However, while radioactivity levels for
both Nguluku and Maumba regions were assessed; elemental analysis for heavy metals
was only carried out for Maumba. A total number of fifty samples were analyzed for
heavy metals using energy dispersive x-ray fluorescence (EDXRF) system which consists
of a radioisotope cadmium-109 source and a silicon-lithium drifted (Si(Li)) detector.
Radioactivity levels of the samples were determined using a high purity germanium
(HPGe) detector.
Iron and titanium were observed as the major elemental constituents of the Maumba soils
with concentration levels of 1.21% and 1.57%, respectively. Zirconium and manganese
levels were also found to be high, with mean levels of 1193.3 μg/g and 822.2 μg/g
respectively. Niobium concentration level was found to vary between (13.77 - 79.24)
μg/g with a mean of 31.81 μg/g in these samples. These levels were found to be lower
than those reported earlier for Mrima Hill soil samples. Concentrations distribution of
titanium and zirconium in the samples were found to have a strong correlation of r=0.97.
Activity concentrations of the three major primordial radionuclides – thorium-232,
uranium-238 and potassium-40 – in the fifty samples from Maumba and seven samples
from Nguluku were assessed. High contributions from Th-232 and U-238 determined as
72.0 and 50.2 Bq/kg in Maumba and 178 and 162 Bq/kg in Nguluku soil samples. These
levels are much higher than the world average of 25 Bq/kg. Contribution from K-40 was
found to be negligible in all the samples analysed. | en |
