Metal-organic complex-bound

In general, TEs in exchangeable and acid-soluble forms are considered to be easily bioavailable (see Table 12.1). The metal-organic complex-bound form is also relatively mobile (Krishnamurti et al., 1995). The reducible and oxidizable forms are relatively stable under standard soil conditions, yet easily reducible and oxidizable fractions may be readily mobilized, as detailed in the ensuing sections. 

Fraction 3. Metal-organic complex-bound 0.1 M Na4P202 (pH 10) (soil/reagent = 1 30) shake for 20 h. 

Metal-organic complex-bound Carbonate-bound... 

Compared with bulk soils, solid-phase speciation of Cd differs substantially in phosphate fertilizer-treated rhizosphere soils (Krishnamurti et al., 1996). The amounts of carbonate-bound Cd and metal-organic complex-bound Cd species of the rhizosphere soils at 2-week plant growth stage, particularly in the soils treated with Idaho phosphate fertilizer, are appreciably higher than those of the corresponding bulk soils (Fig. 4). In comparison to the corresponding bulk soils, the amount of carbonate-bound Cd species of the rhizosphere soils increased by 15-18% in the control soils and by 79-92% in the soils treated with Idaho phosphate fertilizer, whereas the metal-organic complex-bound Cd species increased by 4-7% in the control soils and by 2-3 times in the soils treated with Idaho phosphate fertilizer. The increase in the carbonate-bound Cd... 

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