Soil
contamination has become a major environmental problem in many developed and
developing countries in recent years, because heavy metals in the environment
is of great concern due to their toxicity and threat to human life and environment
(Okoro et al, 2017). Two main sources of heavy metals in the soil are: (i)
natural processes and (ii) anthropogenic processes (Prartoan et al, 2016). Anthropogenic
activities can enhance levels of heavy metals in soils (Jagus et al, 2013) and
they can easily transfer from soil to groundwater (Puga et al, 2015) or crops
(Olu-Owaolabi et al, 2012), and can hazardous affects for plants, animals, and
human health (Jalali and Hemati, 2013; Benhadyya and Hadjel, 2014). Generally, most of soil metals today have originated from anthropogenic
sources (such as industrial activities, automobile emissions, agricultural
practices and etc.) than derived from natural ones (Wei and Yang, 2010; Li and
Feng, 2012; Rodriguez Martin et al., 2014; Karim et al., 2014; Burt et al.,
2014), that in the the meantime, affected with polluted water and industrial
activity is very important (Raman and Narayanan, 2014).

 

Industrial
effluent pollution in environment (Qaiser et al, 2013) is a concern problem due
to the high levels of potentially toxic elements, such as nickel, lead, cadmium,
zinc, and copper (Puga et al, 2015). The availability of heavy metals in soil
is low compared with other elements due to high capacity of soil material to
adsorb heavy metals, soil conditions such as pH, redox potential, cation
exchange capacity and organic matter, which can highly influence metal
assimilation by plant roots, by affecting root growth and the mobility of the pollutants
(Ross, 1994). Research on the availability of heavy metals from soils is
essential for evaluation the absorption fate of heavy metals in soil.

 

The
total concentration of heavy metals may be used as an methods of heavy metals
contamination, but it provides insufficient information about their mobile and availability
forms. The degree of heavy metals absorption by soil is affected by
environmental factors, soil components and properties such as the amount of
heavy metals. Heavy metals exist in soils in various forms having different
availability (Alvarenga et al, 2012). Investigation of various heavy metals
fractions becomes increasingly important in environmental studies and provides
precious information for metal mobility, remediation, and risk assessment
(Jalali and Hemati, 2013). Heavy metals in soil distributed among several
phases which include water-soluble and exchangeable phase, organic associated
phase, inorganic phase, and residual within the primary mineral lattice phase
(Li and Shuman, 1996). Water soluble and exchange fractions are weighed readily
mobile and bioavailable than other fractions, especially a residual fraction, that
solubility in this fraction is lesser than other fractions. Sequential
extraction is widely used to estimate the amounts and proportions of metals in
soil and to predict mobility, avalibility and metals leaching. Fractionation is
also useful to distinguish the metals origin (lithogenic or anthropogenic); anthropogenic
metals mainly occur as liable extractable fractions, whereas those from
lithogenic sources are present in the residual fraction (Salomons and Förstner,
1980; Hooda and Alloway, 1994; Madrid et al., 2004).

 

Anthropogenic
processes generally led to increases of heavy metals in soils and environments
(Sun et al, 2010; Acosta et al, 2011). Iindustrial centers is a one the most important areas
in the world, including Iran. Industrial effluent can be effect as a source of
soil pollution, which can be resulted in serious contamination of soils by
heavy metals (Benmalek et al, 2014). Investigation of soil in around of
industrial area affected effluent can provide a best information about heavy
metals fractionation in contaminated soil. Data on heavy metals fraction in
Hamedan industrial areas are less. This paper assessment the content and the fractions
of heavy metals in some soils of important industrial areas, Hamedan Province
in western Iran. Thus, the objectives of this study were to evaluate the total
content of Ni, Pb, Cd, Zn, and Cu and their fractions in surface soils of industrial
areas to determine mobility and availability in soils.