| dc.description.abstract | In this work. X-ray fluorescence analysis technique
was used to analyze soils. plants. water. sediments and
urine samples from a selected area in the Athi River town.
From the analysis. dust from the electrostatic
precipitator was found to have very low levels of chromium
and 1ead. For the other elements. dust had high 1eve 1s ,
e.g. iron (7480.3 - 9670. 7 ppm) and manganese (404.0 -
595.5 ppm). However. the levels were found to be lower
than those in the indigenous soil in this region e.g. iron
(30180.4 - 53340.7 ppm) and manganese (1320.1 1960.5
ppm) . Overa 11. there was an increase in the 1eve 1s of
these metals with distance from the electrostatic
precipitator. Thus. the metals in the dust were noted to
leach down suggesting they were likely to be available to
plants.
From the analysis of plant leaves. the concentrations
of metals were found" to depend on the levels in the soil.
soil type and the organic matter content except for zinc.
The metals in the indi genous soi 1 appeared to be more
available to plants than those in the dust. Leaves from
the three plant species sampled had significantly
different.levels of heavy metals suggesting that they had
different physiological role. different tolerance or
different mechanisms of absorption.
In the case of the water samples from the Athi river,
the pH values were found to be high (7.20 - 9.45). The
concentrations of the metals encountered were also higher
than the natural uncontaminated levels e.g. copper (4.6
-17.9 ppb) which was much higher than the reported
uncontaminated values (0.2 - 2.2 ppb) for drinking water
although they were lower than the W.H.O. highest
acceptable values. It was noted that as the distance of
the sampling point from the point where a given metal was
being discharged increased, the concentration of the heavy
metals decreased. This suggested that the river load was
within what it could cope up with i.e. removed by the
natural self purification of rivers through the process of
precipitation and scavenging by microorganisms.
The concentration of elements in sediments from the
Athi river were found to be generally high, e.g. chromium
(0 - 428.2 ppm), iron (4970.1 - 14520.3 ppm), manganese
(313.2 -6410.0 ppm), copper (1.6 - 43.7 ppm), zinc (16.4
- 55.7 ppm), lead (3.3 - 32.7 ppm) and mercury (0 - 23.2
ppm). Despite this~ it was noted that that only a small
percentage was in solution. This was probably due to the
high pH of the water, low solubility product and matrix
effects. Generally, the results suggested that the Athi
river was only moderately polluted.
Analy'sis of urine samples from those working in the
cement factory had relatively higher concentrations for
most of the metals than those not working in the factory
(controls) with lead as the only exception. | en |
