International Journal of Aquaculture, 2013, Vol.3, No.15, 79
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84
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82
Table 3 Comparison of hardness level (adapted from Twort and
Dickson, 1994)
Hardness level
0.05
Soft
50
to 100
Moderately soft
100 – 150
Slightly hard
150 – 200
Moderately hard
Over 299
Hard
Over 300
Very hard
Note: Source: Adejuwon and Adelakun, 2012
2
Conclusion
Since most of the parameters measured were above
the maximum permissible limits of the national and
international standards, it can be concluded that the
water is unfit for domestic uses, drinking and
aquacultural purposes and therefore needs to be
treated if it is to be used at all. The low dissolved
oxygen values for the first four months was too low i.e.
< 5 mg/L. This is most likely as a result of the amount
of effluents discharged into the river. To prevent mass
extinction of aquatic organisms due to anoxic
conditions, proper regulations should be implemented
to reduce the organic load the river receives.
3
Materials and Methods
3.1
The Study Area
Ogun State is a state in South-western Nigeria. It
borders Lagos State to the South, Oyo and Osun states
to the North, Ondo State to the east and the republic of
Benin to the west. Abeokuta is the capital and largest
city in the state (NBS, 2012).
3.2
Geography of River Ogun
It (Figure 1) is one of the main rivers in the
southwestern part of Nigeria with a total area of 22.4
km
2
and a fairly large flow of about 393 m
3
secG
1
during the wet season. It has coordinates of 3°28'E and
8
°41'N from its source in Oyo state to 3°25'E and
6
°35'N in Lagos where it enters the Lagos lagoon
(
Ayoade et al
.
, 2004;
Oketola et al., 2006). Two
seasons are distinguishable in Ogun river basin, a dry
season from November to March and a wet season
between April and October. Mean annual rainfall
ranges from 900 mm in the north to 2 000 mm
towards the south. The estimates of total annual
Figure 1 Map of River Ogun showing the Sampling Stations
Note: Source: Google maps, (2012)