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Accueil du site → Doctorat → Egypte → Distribution, partitioning and speciation of some trace metals in cultivated desert soils in the 10th of ramadan region

Benha University (2016)

Distribution, partitioning and speciation of some trace metals in cultivated desert soils in the 10th of ramadan region

Elwa, Abdel-Salam Mohamed Abdel-Salam

Titre : Distribution, partitioning and speciation of some trace metals in cultivated desert soils in the 10th of ramadan region

Auteur : Elwa, Abdel-Salam Mohamed Abdel-Salam.

Etablissement de soutenance : Benha University .

Grade : Doctor of Philosophy (PhD) in Science 2016

Résumé partiel
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 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.

Présentation étendue (EULC)

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