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Contamination of soil with heavy metals (HMs) poses serious risks for biota and human health.Cadmium and Pb are among the most important contaminants of environment.These metals are introduced to soil mainly through mining and smelting operations,phosphorous fertilizers,and by the incorporation of sewage sludge into the soil.The objectives of the experiment described here were to study:i)the influence of aging on the speciation and availability of Cd and Pb in highly polluted soils,ii) The effect of plant residue and NaCl on availability and soluble organic and inorganic species of Cd and Pb in soils.An incubation experiment with OM treatment (20 g/kg of alfalfa powder) and salinity treatment (50 mmol/kg of NaCl) was conducted.Triplicate treated samples (75 g) were incubated in separate polyethylene containers at constant moisture (60% water holding capacity) and temperature (25oC) for 3 months.Subsamples were taken after 1,3,6,and 12 weeks incubation and electrical conductivity (EC),pH,dissolved organic carbon (IOC),concentrations of cations (Cd,Pb,Ca,Mg,K and Na) and anions (CO3,HCO3,PO4,SO4,and Cl) were determined in 1∶2.5 soil:water suspension and available Cd and Pb determined in 0.05 M EDTA,extract.Chemical composition data obtained was used as input data to Visual MINTEQ computer program to calculate concentrations of the soluble inorganic and organic species of Cd and Pb in the extracts.Organic matter and salinity applications decreased pH significantly in both soils and the decreases in the soils pH were relatively consistent with incubation time.Electrical conductivity (EC) of the soils increased significantly by both C1 and OM treatments.Salinity treatment increased total dissolved Cd concentration in both soils and that of Pb only in the soil 1.EDTA-extractable Pb in the soil 1 and EDTA-extractable Cd in the soil 2 increased significantly by OM application.This treatment also had an increasing effect on the concentrations of total dissolved Cd in both soils and that of Pb only in soil 1.an important point was that total dissolved Pb concentration decreased in the soil 2 with the applications of OM and salinity.