Transport of Escherichia coli strains isolated from springs in Kampala, Uganda - Transport of Multiple Escherichia Coli Transport in Saturated Porous Media - page 107

(7 out of 40, or 18%) were all subject to considerable kinetic attachment, and their maximum
relative breakthrough concentrations were therefore rather low: between 0.06 and 0.48.

7.4.4. Correlation between cell properties and model parameters
The relations between measured cell properties, parameters obtained from HYDRUS
modeling and also maximum peak relative breakthrough concentrations were analysed using
Spearman's Correlation Test ( Table 7.3 ) .

Table 7. 3: Correlation matrix for (C/C0)max, measured cell properties, and model

parameters (Α, f, Ω, ks)

C/C 0 ) max Α f k s Cell Motility Zeta Hydrophobicity

Ω

aggregation potential

Cell aggregation -0.180 -0.059 -0.052 -0.023 0.219

Motility -0.059 -0.024 0.018 -0.099 0.054 0.154

Zeta potential 0.215 0.368 -0.179 0.394 -0.116 -0.068 -0.369

Hydrophobicity 0.048 -0.284 0.269 -0.275 -0.044 -0.023 -0.092 -0.046

Average Size -0.071 0.117 -0.263 0.073 -0.009 -0.080 0.074 -0.257 -0.050

From Table 7.3 , we concluded that there was no statistically significant correlation between
neither of the measured cell characteristics nor between any of the measured cell
characteristics and the parameters obtained from modeling. Four identified O-serogroups
were grouped and one way ANOVA was applied to compare mean values of transport
characteristics and measured cell properties between the groups. Results indicated that with
the exception of f which showed a significant ( p = 0.021) different mean value between
serogroups O21 and O108 mean values of transport characteristics for the serogroups (O14,
O21, O91 and O108) were not significantly different between the groups, with high p values
( p > 0.05) (for Α, p = 0.254; for Ω, p = 0.605; for (C/C 0 ) max, p = 0.657; for k s , p = 0.833; for
k a , p = 0.276). Average values of cell properties grouped according to the four O-serogroups
did not show any significant difference among their mean values (for cell aggregation, p =
0.531; Motility, p = 0.156, zeta potential, p = 0.534; hydrophobicity, p = 0.483, size, p =
0.818).

7.5 Discussion
An important conclusion from our work was that almost all springs we sampled had high
concentrations of thermotolerant coliforms, nitrate and chloride, whereby nitrate and chloride
were correlated. This suggested that waste water, which is so abundantly present and
disposed of freely in Kampala was the source of contamination of the springs. Our findings
are not new: also Howard et al (2003) and Kulabako et al., (2007) identified multiple sources
of anthropogenic contamination of the shallow aquifer from which most of the springs tap
their water: solid waste dumps, pit latrines, unlined grey water channels or grey water
polluted unlined storm water drainage channels are all prevalent in most of the Kampala area.
Also, spring protection was not optimal: protective fences were broken and faulty allowing
free-range cattle and other domestic animals to access the site and thereby increasing the