1. Introduction
Anthropogenic activities are considered to be the foremost
responsible for soil enrichment in toxic heavy metals, even though
these pollutants may also be natural constituents of the soil. Industrial
processes, mining exploration, manufacturing and disposal
of some waste materials are examples of mankind actions that can
introduce in the soil non-essential metals with phytotoxic and
zootoxic properties (Park et al., 2011; Wuana and Okieimen, 2011).
The risk that these contaminants pose to the environment and
human health is directly related to their bioavailability in soil