الفهرس 
REVIEW OF LITERATUREOnly 14 pages are availabe for public view
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Abstract
The distribution, partitioning and speciation of six trace metals were investigated in eight soil profiles representing the soils of the 10th of Ramadan Region. characterization of soils was performed through the determination of the relevant soil morphological, physical, chemical and mineralogical characteristics. The selected trace metals , Zn, Cu, Ni,Co, Cr and Cd were determined in the surface, subsurface layers and beneath in each soil profile. Besides, these trace metals were also determined in irrigation water and plant parts of crops grown on the studied soils (range plants and pastures, vegetables and fruit orchards).
Regarding soils, the total trace metals concentration were determined and elements liabilities were evaluated by extraction with DTPA. Moreover , speciation studies of trace metals were conducted by sequential extraction which was used for chemical differentiation of each trace metal into chemical fractions (forms) in order to assess the potential mobility and bioavailability of these metals in the studied soil profiles. This also allows subdividing the total trace metals content into fractions representing portions bound to different soil components. The frequency and depthwise distributions of total, chemically extractable and trace metals forms were defined and presented. These patterns of distribution are in most cases non uniform and non-specific regardless of certain trace metals. Data also show that the residual fraction is the most abundant form for all trace metals under study where it constitutes average percentages of about 87,69,75,98,84 and 49% of the total content of Zn,Cu,Ni,Co,Cr,and Cd, respectively. The Fe-Mn bound form is of next importance with average percentages of about 10,4,4,5,9 and 17 of the total content of Zn,Cu,Ni,Co,Cr,Cd, respectively . In contrast, low to very low amounts of the concerned trace metals are associated with water soluble, exchangeable, carbonate bound and organic bound forms where their average percentages do not exceed 2.5 % of total trace metals content, The relationship between each form of trace metals with
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soil variables that control its behavior in soils and also between each form and other forms of the same trace metals were statistically evaluated through correlation coefficients and regression equation. The low mobility factor coupled with high levels of residual form of the concerned trace metals dictate that the metals do not pose any environmental risk or hazard while the converse is true for higher mobility factor.
Trace metals in irrigation water.
Soluble trace metals vary considerably with the type of irrigation water (Nile water, groundwater ,drainage water and mixed water ).For instance , soluble Zn and Cu are relatively high in Nile Water while Ni, Co and Cr are entirely absent in Nile water and Cd is at a minimum level . In drainage and mixed waters, most trace metals are found in appreciable amounts whereas groundwater is characterized by relatively low to very low Zn and Cu concentrations
Trace metals in plants grown on the studied soils.
Concerning grown plants, the trace metals under study either micronutrients (Zn,Cu, Ni)or pollutants (Cd) in the soil–plant system are largely of concern for agriculture or agronomy, ecology and environmental importance .Co and Cr are not essential to plants but are important for animal and human health. The obtained results dictate that trace metals in roots, leaves and fruits vary considerably from one plant species to another and even within the same species. The data also indicate bioaccumulation of some, if not all, trace metals in certain plants.
Quantification of pollution index.
Computation of single element pollution index (SEPI ) and combined pollution index( CPI ) indicates high pollution of Cd followed by Ni,Cr,Cu and Co with no signs of Zn pollution.
Enrichment factor is also calculated for the concerned trace metals to shed light on contamination by certain trace metals or metal.