Bioscience Methods 2017, Vol.8, No.1, 1-18
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1.3.2 Contamination degree
Contamination degree
(CD) is sometimes known as degree of contamination. CD is the sum of all contamination
factors, which provides information about total contamination in a particular sampling location (Singovszka et al.,
2014; Bhutiani et al., 2017). Contamination degree 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), Todorova et al. (2016), Ghaleno et al. (2015), 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), Qingjie et al. (2008), Odukoya et al. (2016).
CD =
∑ +
+ +
+ + +
+
+
(Equal 2)
1.3.3 Pollution load index
Pollution load index (PLI) gives information about the toxicity of the metal in each respective sample locations
(Tomlinson et al. 1980; Ghaleno et al., 2015; Bhutiani et al., 2017). PLI was computed based on the formula
previously described by Tomlison et al. (1980) and widely applied by Suresh et al. (2011), Wang et al. (2016),
Ghaleno et al. (2015), Bhutiani et al. (2017), Tang et al. (2014), Hassaan et al. (2016), Ghazaryan et al. (2015),
El-Metwally et al. (2017).
PLI =
√
x
n
(Equal 3)
CF is the contamination factor for the respective metals and n is the number of elements (n = 9).
1.3.4 Pollution index and Nemerow integrated pollution index
Pollution index (PI) and Nemerow integrated pollution index (NIPI) is another type of indices used to assess
extent of pollution in an industrial area (Cheng et al., 2007; Sarala and Sabitha, 2012). NIPI considers the overall
level of soil pollution, taking into account the concentration of the various heavy metals under consideration
(Guan et al., 2014; Kowalska et al., 2016; Mazurek et al., 2017).
PI has the same formula with CF. But unlike CF, PI consider the mean concentration of heavy metals from at least
five locations/stations. PI formula has been previously described by Yu et al. (2004), Yang et al. (2011) and has
been widely applied by Jiang et al. (2014), Al-Anbari et al. (2015).
P1 =
Concentration of individual metals
Background value
(Equal 4)
NIPI considers all the individual metals investigated from equation 4 (Al-Anbari et al., 2015). NIPI can be used to
assess the quality of soil (Liang et al., 2011). NIPI have been widely employed by authors in assessing risk
pollution potentials of heavy metals in the environmental especially soil (Liu et al., 2004; Yu et al., 2004; Cheng et
al., 2007; Yang et al., 2011, 2013; Sarala and Sabitha, 2012; Jiang et al., 2014; Al-Anbari et al., 2015).
Nemerow integrated pollution index (NIPI) =
√
PI
mean
2
+ PI
Maximum
2
2
(Equal 5)
Where
PI
mean
2
is the mean value of PI of individual heavy metals and
PI
Maximum
2
is the maximum PI value of
individual heavy metals.
1.3.5 Pollution index (contamination index)
Pollution index (contamination index) (PI/CI) is often used in identifying pollution in priority areas (locations)
(Sarala and Sabitha, 2012). According to Sarala and Sabitha (2012), PI/CI requires several measurements in the
same sampling site. PI/CI was developed by Johansson and Johnsson (1976) and Ott (1978) and has been applied
by Sarala and Sabitha (2012).
PI/CI =
∑
1
(Equal 6)
