Impact of some heavy metals on soils irrigated with waste water

الملخص EN

Heavy metals movement in soil profiles is of major environmental concern because even slow transport through the soil may eventually lead to deterioration of groundwater quality.

In this study, four metal contaminated soil profiles were selected from croplands where waste water from 10th of Ramadan City, henceforth named Ramadan city, had been applied annually for periods of 8 to 25 years.

One uncontaminated soil from the same physiographic area was also sampled as a control.

The distribution and chemical fractionation of heavy metals retained in the soils were examined.

Soil samples were collected in 30 cm increments from the surface to 120cm depth.

Total content of Mn, Cu, Zn, Pb, Co and Ni in the soil samples were determined.

To better understand metal movement in relation to metal fractions in the soil profiles, soil samples were also extracted sequentially for exchangeable, adsorbed, organic, carbonate and sulfide fractions.

The soils receiving waste water had significantly higher concentrations of total Mn, Cu, Zn, Pb, Co and Ni than the untreated soil.

Concentrations declined significantly with soil depth. The sequential extraction results from untreated and treated soils show that the major portion of Mn, Zn, Co and Ni was associated with the sulfide fraction, while the major portion of Cu and Pb was associated with the organic and carbonate fractions Addition of organic wastes leads to an increase of heavy metals concentrations in the growing plants with different values in roots and shoots, and period of organic wastes addition.