ABSTRACT
To study soils and plants pollution with heavy metals and remediation
techniques, five pot experiments were carried out. A surface clay soil sample
was collected (0 – 20 cm) and prepared for experiments. Ni, Cd, Cu and Zn
metals were chosen for this study. The first experiment was conducted on the
chosen metals (in carbonate form) with different concentrations for each metal.
Whereas, the experiments from 2 to 5 were conducted in sulphate form (0.5%
Ni, 0.25% Cd, 1% Cu and 1% Zn of soil weight). The conducted experiments
were carried out in two replicates for each treatment. Chemical amendments
(CaCO3, CaHPO4 and CaSO4.2H2O) were added in 0, 2, 4 and 6% for each
metal in experiments 2, 3 and 5, respectively. Whereas, NH4H2PO4
amendment was added in 0, 1 and 2% in experiment 4. The metals and
amendments were mixed well with soil pots. All treatments were planted with
barley and fenugreek then irrigated with nutrient solution (experiments 1, 2, 3
and 5) and distilled water (experiment 4). After 35 days, all plants were totally
collected, washed well, dried, weighted and prepared for metal determination.
This process was repeated three times. The obtained results showed that metals
uptake by barley and fenugreek increased as the metal in the soil increased.
Addition of chemical amendments to polluted soil differ in their effects on
reducing uptake of Ni, Cd, Cu and Zn metals by cultivated plants, depending
on soil pH, type of metal, type of amendment, rate of amendment, plant species
and characteristics. Generally, the used amendments in this study reduced
DTPA-extractable and uptake (except in some cases) of Ni, Cd, Cu and Zn by
cultivated plants in polluted soils. More studies are needed to answer and solve
the problems of soils and plants pollution with heavy metals.