Bioscience Methods 2017, Vol.8, No.1, 1-18
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Table 6 presents the Nemerow integrated pollution index (NIPI) of heavy metals concentration in cassava mill
effluents contaminated soil. NIPI ranged from warning line of pollution (NIPI≤0.7) to high level of pollution
(NIPI>3). Under BMM consideration, there was low level of pollution (1<NIPI≤2) apart from cobalt in dry season.
Variation exist under both scenarios in wet season, thus copper, zinc, manganese, iron, cadmium and cobalt
showed low pollution, chromium and nickel showed moderate level of pollution while lead showed high level of
pollution. Like dry season BMM consideration, dry season of BGM indicate low level of pollution in all the
metals. While in wet season of BGM consideration, copper, zinc, manganese, iron, chromium and cobalt showed
low pollution, lead and cadmium nickel showed moderate level of pollution while lead showed high level of
pollution. The moderate/high pollution in lead is an evident of considerable contamination. While the moderate
pollution in nickel and cadmium is an evident of moderate contamination. The slight variations that exist between
both backgrounds suggest the differences in the mean value used in the study. In NIPI pollution categorization, it
appears that dry season has lower pollution compared to wet season from the cassava mill effluents contaminated
environment.
Table 6 Nemerow integrated pollution index of heavy metals concentration in cassava mill effluent contaminated soil
Parameters
BMM
BGM
Dry
Wet
Dry
Wet
Cu
1.44
1.16
1.46
1.10
Zn
1.01
1.09
1.35
1.24
Mn
1.18
1.18
1.43
1.30
Fe
1.35
1.16
1.54
1.13
Pb
1.64
3.27
1.79
2.79
Cd
1.00
1.78
1.00
2.36
Cr
1.46
2.20
1.35
1.93
Ni
1.37
2.74
1.29
2.14
Co
0.98
1.80
1.25
1.37
Note: NIPI≤0.7 (No pollution); 0.7<NIPI≤1 (Warning line of pollution); 1<NIPI≤2 (Low level of pollution); 2<NIPI≤3 (Moderate
level of pollution); NIPI>3 (High level of pollution); BMM- Background Median Mean; BGM- Background Geometric Mean
Table 7 presents the pollution index (contamination index) (PI/CI) of heavy metals concentration in cassava mill
effluent contaminated soil in a rural community in Delta state, Nigeria. The PI/CI showed that the soil were
between unpolluted to low polluted except for few instance viz: copper in dry season for LB, lead of wet and dry
season for LC and CE, and wet season for LA and LE which were within low pollution to moderately polluted.
Table 7 Pollution index (contamination index) of heavy metals concentration in cassava mill effluent contaminated soil
Location
Seasons
BMM
Cu
Zn
Mn
Fe
Pb
Cd
Cr
Ni
Co
LA
Dry
1.23
1.20
1.16
1.14
1.35
1.22
1.28
1.40
1.47
Wet
1.04
1.09
1.15
1.13
1.12
1.22
1.30
1.66
2.53
LB
Dry
2.33
1.23
1.20
1.08
1.18
1.22
1.57
1.54
1.13
Wet
1.04
1.13
1.40
1.05
1.39
1.12
1.64
1.22
0.00
LC
Dry
1.10
1.29
1.17
1.05
1.13
1.22
1.23
1.40
1.05
Wet
1.11
1.17
1.25
1.07
2.25
1.22
1.64
1.10
0.00
LD
Dry
1.19
1.06
1.16
1.08
1.35
1.22
1.14
1.20
1.18
Wet
1.09
1.03
1.10
1.09
1.12
1.22
1.62
1.32
0.00
LE
Dry
1.33
1.07
1.13
1.07
2.16
1.22
1.17
1.29
1.09
Wet
1.05
1.13
1.10
1.08
1.32
1.46
1.16
1.45
2.07
Note: 1= unpolluted; 2= Low polluted; 3 = moderately polluted; 4 strongly polluted; 5; extremely polluted.
BMM- Background Median Mean; BGM- Background Geometric Mean
Figure 3 presents the average pollution index using median mean for heavy metals concentration in cassava mill
effluent contaminated soil in a rural community in Delta state, Nigeria. The average index was greater than 1 in
