Biological Evidence 2018, Vol.8, No.3, 21-31
28
background scenarios. Furthermore, in median mean consideration, all the quantification of contamination was
0.000% for location B, and positive for geometric mean scenario. Location C showed negative quantification of
contamination except for cobalt that was 0.000% under both considerations. The positive values result suggests
that pollution/contamination in the study locations are due to anthropogenic sources (Bhutiani et al., 2017; Izah et
al., 2017c). The difference among the various locations suggests variation in the anthropogenic activities in each
of the locations. This trend has also been reported by Bhutiani et al. (2017), Izah et al. (2017c).
Table 7 presents the ecological risk (ER) and ecological risk index (R’) of heavy metals in sediment of Nun river
in Bayelsa state, Nigeria. The ecological risk index were within low risk (ER < 40) except for cadmium in location
A and B which was within moderate risk (Er 40 ≤ Er < 80) under geometric mean consideration. The higher
ecological risk of cadmium in this study could be due to the higher toxic factor (Zhu et al., 2012; Ghaleno et al.,
2015; Izah et al., 2018). Typically, cadmium has no known biological activity on living things; as such its presence
in living organisms could be detrimental to the living organisms even at low concentration (Ghaleno et al., 2015;
Izah et al., 2016; 2018). The ecological risk index showed low risk (R’<150) of heavy metals in all the locations.
This suggests that on the overall, concentration of heavy metals in the sediment may not be able to cause any
major shift in the sediment balance.
Table 6 Quantification of contamination (%) of heavy metals concentration in sediment of Nun River at Gbarantoru and Tombia
towns in Bayelsa state, Nigeria
Parameters
Median mean
Geometric mean
QoC
Location A
Location B
Location C
Location A
Location B
Location C
Cd
8.330
0.000
-120.000
33.333
27.270
-60.000
Cr
33.333
0.000
-1.000
33.333
0.000
-1.000
Co
50.000
0.000
0.000
50.000
0.000
0.000
Ni
62.500
0.000
-1100.000
7.500
33.333
-700.000
Pb
23.529
0.000
-85.714
29.412
7.692
-71.429
Zn
12.698
0.000
-34.146
17.460
5.455
-26.800
Fe
21.338
0.000
-78.985
29.936
10.931
-59.420
Table 7 Ecological risk of the heavy metal concentration in sediment of Nun River at Gbarantoru and Tombia towns in Bayelsa state,
Nigeria
Parameters
Median mean
Geometric mean
Ecological risk (ER)
Location A Location B
Location C
Location A
Location B
Location C
Cd
32.733
30.000
13.650
45.000
41.250
18.750
Cr
3.000
2.000
1.000
3.000
2.000
1.000
Co
10.000
5.000
5.000
10.000
5.000
5.000
Ni
13.335
5.000
0.415
20.000
7.500
0.625
Pb
6.540
5.000
2.690
7.085
5.415
2.915
Zn
1.271
1.000
0.559
1.427
1.122
0.627
Comparison criteria
Note: Er < 40 (Low risk); Er 40 ≤ Er < 80 (Moderate risk); 80 ≤ Er < 160 (Considerable); 160 ≤ Er <
320 (High); Er ≥ 320 (Very high)
Ecological risk Index (R’) 66.879
48
23.314
86.512
62.287
28.917
Comparison criteria
Note: R’ <150 (Low risk); 150 ≤ R’ < 300 (Moderate risk); 300 ≤ R’ < 600 (Considerable); R’ ≥ 600
(Very high)
3 Conclusions
In coastal region of Bayelsa state, several water bodies exist and are called by different names including creeklets,
creeks, streams, rivers, ponds, lakes etc. In Bayelsa state, Nun River is a major water systems that bifurcate
through the area and emptied into the ocean through the estuaries. At different locations most of the rivers have
different names depending on the community. The river system is a major recipients of municipal wastes stream in
the area. Furthermore, several anthropogenic activities are carried out in the shores of the river system. This study
