الفهرس 
Distribution of heavy metals in some contaminated soils and growing trees in Egypt and Tunisia
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Abstract
The present study was conducted to investigate the accumulation in soils, trees and mobility of diferent chemical fractions of heavy metals (Cd, Cu, Pb, Fe, and Mn) with different sources of pollution. The soil profile samples were collected from 3 sites from each of El-Gabal El-Asfer, Abbou-Rawash, and El-Asher min Ramadan area which received sewage sludge and sewage effluent for long time also, El-Asher min Ramadan area which was contaminated by industrial wastewater. The trees samples were taken from the same locations of soil samples. Results revealed that soil pH and total carbonate content were slightly decreased as the irrigation period increased. Meanwhile, total contents (Cd, Cu, Pb, Fe, and Mn) of soils, increased as the irrigation period increased. Total contents exceeded, in cases, and / or reached, in some ones, the maximum permitted loadings. Inaddition, DTPA-Extractable (Cd, Cu, Pb, Fe, and Mn) increased continuously in the studied areas which received sewage sludge or effluent and industrialmaterials for a long time. Bioavailable portions were found to represent a great deal of the total contents. The low percentage of total extracted may be ascribed to its precipitation as CaCO₃. These results gave an evidence of high availability of sewage effluent burden-metals to trees. There were negative correlation confections between DTPA extractable-Cd and each of pH and CaCO₃ and positive correlations with total organic matter and clay contents. Distribution of the studied methods among correlations different chemical fractions showed the prevalent of immobile pools. In general, they follow the order; residual, organic, Fe&Mn-oxides, carbonates and exchangeable forms. Results showed high movement of sewage effluent-burden heavy metals down the soil profile.The concentrations of heavy metals (Cd, Cu, Pb, Fe, and Mn) in leaves of trees increased with increasing the irrigation time period of sewage effluent, sewage sludge and industrial weastwater application to soils. The absolute values of these metals in leaves of tree are different from metal to another, depending on the contents and the availability of these metals in the soil which are controlled by different soil parameters (CaCO3, pH, EC, clay and soilorganic matter). The values of these metals followed the order of (Cd {u02C2} Cu{u02C2} Pb{u02C2} Fe < Mn). The values of these metals accumulation were higher in leaves of trees under study. Generally, using low water quality in irrigating trees, should take in consedration the amount of heavy metal contents and type of trees cultivated, time of irrigation and age of trees