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Abstract
Heavy metals such as nickel and cobalt are toxic to higher plants and become one of the most environmental problems that facing mankind. To predict bioavailability, and hence potential toxicity or deficiency, and ultimately the impact of heavy metals on plan’, animals imperative TO understand metal-soil infarctions at fundamental level. The deficiency 01’ toxicity of heavy metal ill ecosystems depend nor only Oil the total metal concentration, bl1’ also more si!U the soli, ability 10 sorb and release metal ions from solid phase to replenish those removed from solution by plant. Therefore, il is now gel1t$llly accepted 11Ial opioid encryption reactions of the surface of Beth inorganic and organic soil colloidal materials govern metal concentrations illtile. soil solution. Regeneral and nickel as well a cobalt ill particular call be introduced soil and water environmeurs from both augural (as reaction product dieselslim of Mrals) and aurhropogeuie (agricultural application of sewage sind and fertilizers, and lor rnroegh land disposal of metal-contaminated municipal and industrial wastes) sources (Wang and Xing. 2002; however. metals inputs in soil can rake several parhwa depending 011 the so’l ably to sorb-desorb or retain and store them accordin 10 rhe uarure behaviour of its constituents it well asrelative metals affinities for these surfaces to form strong complexes. The maiu goal of this rudy was to evaluate the factors that chemical behaviour of iand ill soil. Fulfilling such a goal required throwing some ’he effect of rhe domain and effective soil eparare precipitation of both, Counder different concentration of these metals at different soil pH values Moreover. desorption of the previously adsorbed and precipitated