Bioscience Methods 2017, Vol.8, No.1, 1-18
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Table 2 Degree of contamination and contamination factor used to assess environmental pollution
Indices
Low risk
Moderate risk
Considerable
·
Contamination factor (CF) CF<1
1 ≤ CF<3
3≤ CF<6
CF ≥ 6
Contamination degree (CD) CD<8
8 ≤ CD<16
16 ≤ CF<32
CD>32
Note: Hakanson (1980) and have been widely applied by Bhutiani et al. (2017), Singovszka et al. (2014), Soliman et al. (2015),
Todorova et al. (2016), Fiori et al. (2013), Karydas et al. (2015), Zhu et al. (2012)
Table 3a Pollution load (PLI, NIPI and PI) used for assessing environmental pollution
Pollution load index No pollution -
Moderate
pollution
Heavy pollution Extremely heavy
pollution
Tomlison et al., 1980;
Bhutiani et al., 2017;
Ghaleno et al., 2015
PLI<1
-
1<PLI<2
2<PLI<3
3<PLI
Nemerow integrated
pollution index
(NIPI)
No pollution Warning line of
pollution
Low level of
pollution
Moderate level
of pollution
High level of
pollution
Yang et al., 2011;
Jiang et al., 2014;
Yu et al., 2004
NIPI≤0.7
0.7<NIPI≤1
1<NIPI≤2
2<NIPI≤3
NIPI>3
Pollution index (PI)
No pollution Low pollution Moderate
pollution
High/strong
pollution
Very high/strong
pollution
Yang et al., 2011;
Jiang et al., 2014; Yu
et al., 2004
PI≤1
1<PI≤2
2≤PI≤3
3PI<5
PI>5
Table 3b Index performance evaluation criteria for some integrated pollution indices as applied for MPI
Criteria
MPI Indices performance evaluation criteria:
Representativity
1
This is the capacity to provide a spatially representative picture of the environmental states
and the associated impacts.
Comparability
1
This involves the existence of a target level or threshold against which to compare it so that
users are able to evaluate the significance of the values associated with it.
Sensitivity and Robustness 1
This involves the responsiveness to change in the environment.
Credibility
2
This provides a good theoretical basis in technical and scientific terms
Acceptability
2
This gives information about an acceptable levels of uncertainty
Simplicity
3
This provides the ease of calculation and interpretation.
Note: Sarala and Sabitha (2012), Caeiro et al. (2005)
1.3.1 Contamination factor
Contamination factor (CF) is used to assess contamination level in relative to average concentration of the
respective heavy metals in the environment i.e. soil to the measured background values from previous study with
similar geological origin or uncontaminated soil (Sutherland, 2000; Tijani et al., 2004; Uriah and Shehu, 2014).
CF is often expressed based on the formula previously described by Hakanson (1980) and have been applied by
Bhutiani et al. (2017), Uriah and Shehu (2014), Singovszka et al. (2014), Soliman et al. (2015), Ghaleno et al.
(2015), Todorova et al. (2016), Fiori et al. (2013), Karydas et al. (2015), Zhu et al. (2012), Elias et al. (2014),
Mohseni-Bandpei et al. (2016), Swarnalatha et al. (2013), Hassaan et al. (2016), Vowotor et al. (2014), Ghazaryan
et al. (2015), Odukoya et al. (2016).
Contamination factor =
Concentration of the respective metal in the contaminated soil (Cm)
Background values from similar geological area (Bm)
(Equal 1)
Cm is the mean concentration of each metal under study, while BM is the background concentration.
