This work represents a trial towards ameliorating soil polluted with
some heavy metals (Ni, Co and Cd) resulted from some anthropogenic
activities, i.e., human domestic and industrial wastes. To archive this target,
an incubation pot experimental was conducted on two contaminated soil
samples collected from El-Gabal El-Asfar farm (Qalubia Governorate) and
El-Saff (Giza Governorate), which irrigated with sewage effluent and
industrial wastewater, respectively. Before executing this experiment, the
studied two soils were thoroughly mixed with two soil amendments, i.e.,
rock phosphate and calcium carbonate at a rate of 2 % for each one, then
daily wetted with distilled water to a constant moisture content (field
capacity). Soil samples were taken at incubation periods of 0, 25, 50 and 75
days to determine EDTA extractable Ni, Co and Cd for evaluating the
effective role of the tested soil amendments in immobilizing the dominant
heavy metal ions. The obtained results could be summarized in the
following:
1. Increasing time of incubation period between the studied two soils and
rock phosphate caused progressively decreased in the values of EDTAextractable Ni, Co and Cd. The sorbet amounts of Ni, Co and Cd
increased with prolonging time of contact between rock phosphate and
soil, with the removal percentages followed the descending order: Cd >
Ni > Co. The later sequence was changed at the incubation period of 75
days in El-Gabal El-Asfar soil, where the sequence of removal
percentages became: Cd > Co ≥ Ni. Also, El-Gabal El-Asfar soil could
be adsorbed higher amounts of Ni, Co and Cd than El-Saff soil, while
the reverse was true for the sorption percentages of these metal ions in
El-Saff soil, except for Cd at the incubation period of 75 days.
2. Increment of incubation time between soils and CaCO3 led to markedly
decreased in the amounts of EDTA-extractable Ni, Co and Cd, which
seemed a highest capacity with Ni, lowest with Co and intermediate
with Cd. Consequently, it could be categorized these metal ions
according to their removal amounts into the following the descending
order: Ni > Cd > Co regardless of type of soil. The later sequence also
represented the removal capacity of CaCO3 for the studied metal ions.