Bioscience Methods 2017, Vol.8, No.1, 1-17
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Heavy metals enter into the soil through natural or anthropogenic sources (Hernandez et al., 2003; Wang et al.,
2012; Rivera et al., 2015; Mazurek et al., 2017). Natural source of heavy metals in the environment is related to
lithogenic and pedogenic processes (Kabata-Pendias, 2011; Mazurek et al., 2017). Anthropogenic (human)
activities also contribute to heavy metals concentration in the environment.
Most industrial and agricultural activities lead to the release of toxic substances into the receiving environment
including soil, air and water. One of the major pollutant releases into the environment from most industrial and
processing outfit is heavy metals. According to Idris et al. (2013), Izah et al. (2016b; 2017b,c), heavy metals are
metalloid with density higher than 5 cm
2
or 5 times denser than the density of water. Wang et al. (2010) also
described heavy metals as one of the major substance that causes global environmental pollution. The toxicity of
heavy metals on the environment may be due to their ability to persistent and bioaccumulate (Ghazaryan et al.,
2015; Hassaan et al., 2016; Izah and Angaye, 2016). Heavy metals in the environment (soil and water) are
up-taken by some living things in the environment and stored faster than they can metabolize (Hassaan et al.,
2016). For instance, in water/sediment, fisheries tend to biaccumulate heavy metals in their body parts including
muscle, bone, liver, kidney, blood etc (Izah and Angaye, 2016). As such, heavy metals could pose a significant
threat to human health irrespective of the environment (water and soil) (Ghazaryan et al., 2015).
Heavy metals are typically classified into two major forms including essential and non-essential metals. Essential
heavy metals have beneficial role in living things at certain concentration. Some of these important heavy metals
include iron, manganese, copper, zinc, chromium among other. High concentration of essential metals in
biological system could lead to toxicity on the exposed organisms. While other, such as lead, cadmium, mercury
and arsenic have no known role on living organisms. As such they are highly lethal even at low concentration.
In recent time, an elevated concentration of heavy metals in soils in many regions of the world is a major source
of concern especially in developing nations (Zhou et al., 2016). The worry of heavy metals in soil could be due to
their ability to resist biodegradation, toxicity and accumulative characteristics (Mohseni-Bandpei et al., 2016).
Studies on soil heavy metals are mainly focused on heavily urbanized areas including industrial areas and city
agglomerations, as well as on the areas of constant and linear emitters, which include industrial plants, waste
landfills and roads (Al-Anbari et al., 2015).
In Nigeria several studies have been carried out on the impact of wastes and other industrial activities on soil
quality. Specifically, cassava mill effluents which account for about 16% of total weight cassava (Ohimain et al.,
2013c) have been reported to have impact on soil quality including microbial (Nwaugo et al., 2007, 2008;
Ehiagbonare et al., 2009; Okechi et al., 2012; Omotiama et al., 2013; Ezeigbo et al., 2014; Ibe et al., 2014; Eze
and Onyilide, 2015; Igbinosa and Igiehon, 2015; Omomowo et al., 2015), physicochemical (Nwaugo et al., 2008;
Eneje and Ifenkwe, 2012; Nwakaudu et al., 2012; Okechi et al., 2012; Osakwe, 2012; Chinyere et al., 2013;
Izonfuo et al., 2013; Eze and Onyilide, 2015) and heavy metals characteristics (Nwakaudu et al., 2012; Osakwe,
2012; Igbinosa, 2015; Igbinosa and Igiehon, 2015).
Several pollution indices are available in literature for the assessment of environmental quality (Hakanson et al.,
1980; Tomlinson et al., 1980; Liu et al., 2004; Cheng et al., 2007; Qingjie et al., 2008; Yang et al. 2011, 2013;
Sarala and Sabitha, 2012; Guan et al., 2014; El-Metwally et al., 2017; Gasiorek et al., 2017) with regard to some
environmental components (soil, water and sediment). According to Sarala and Sabitha (2012), the use of varying
algorithms could lead to discrepancy on pollution evaluation in an environment (such as sediment and soil). As
such, its essential to use appropriate and/ or best fit method to evaluate environmental components such as soil
and sediment for effective decision making and spatial planning (Sarala and Sabitha, 2012). Specifically, pollution
index and or/ contamination indices is an important tool for processing, analyzing, and conveying raw
environmental information to decision makers, managers, technicians, environmentalist and the general public at
large (Caeiro et al., 2005; Sarala and Sabitha, 2012).
Several authors have widely assessed pollution load and or/ contamination indices of heavy metals in an industrial
environment viz: soil, water and sediment using different pollution load indices (Hakanson, 1980; Tomlinson et al.,
