| dc.description.abstract | Energy- dispersive X-ray fluorescence technique (EDXRF)
utilizing experimentally determined fundamental parameters
was employed for quantitative analysis of elements in various
samples from geothermal areas in the Rift Valley~ Kenya. The
procedure involves preparing thin-film and transparent
specimens and analysing them using the energy-dispersive
X-ray spectrometer with Cd-l09 as the excitation source.
At Olkaria geothermal area~ the wide variety of samples
analysed included water, steam condensates, soil and plant
leaves from eight different wells. The heavy elements found in
these samples were Mn, Fe, Cu, Zn, Pb, and Hg. In some few
cases As was detected in the thermal fluids, in as high
concentration as 0.5 mg/L. Other elements included Ti, Cr, Mo,
Br, and Zr.
The well thermal waters from five wells under exploration
at Eburru geothermal field, sampled at different depths below
the earth's surface show maximum concentrations (mg/L) of the
trace elements as 4:Mn, 18:Fe, 10:Cu, 3.2:Zn, 10:Pb and 0.3:Mo.
Hotsprings from Bogoria and Magadi geothermal fields had
a similar chemical composition of a few heavy metals Mn~ Fe,
Cu, Zn, Pb and Ti existing in low concentrations, below 1 mg/L
with exception of Fe in a few hotsprings. Lakes Magadi and
Bogoria, being fed by these springs and other suspected
underneath sources, are highly saline lakes.
From the elemental data, the cause of environmental
pollution resulting into poor vegetation and scarcity of
animals at the environs of the developed Olkaria Geothermal
Power Plant, producing about MWe, has been deduced as
due to toxic and heavy trace elements. Other applications of
the trace data in geothermal research such as deducing the
nature of geological setting and cold/hot water mixing plus
the general geochemistry of the thermal fluids in above
mentioned areas are discussed. | en |
