Robert S. Bowman, Michael E. Essington, G. A. O’Connor1
1Graduate Research Assistant, Research Assistant, and Professor of Agronomy, respectively, Dep. of Agron., New Mexico State Univ.
Tóm tắt
AbstractSorption/desorption isotherms were used to evaluate the effects of solution composition on the retention of nickel (Ni) by soils of varying physical and chemical properties. Soils examined included agricultural soils of New Mexico, as well as soils from potential chemical waste disposal sites. Sorption of Ni from 0.01N CaCl2 was extensive for all samples: more than 99% of added Ni was sorbed in some cases. Desorption in 0.01N CaCl2 was slight (extreme hysteresis). Ability to extract sorbed Ni with diethlyenetriaminetetraacetate (DPTA), however, indicated that Ni sorption was not completely lrreversible. Increasing the CaCl2 concentration to 0.1N lowered Ni sorption by up to 40%. This was due primarily to direct sorption competition by Ca, rather than to increased Ni‐Cl complex formation, as shown by parallel experiments using Ca(ClO4)2. Presence of small amounts of ethylenediaminetetraacetate (EDTA) in the equilibrating solution lowered Ni sorption by up to 98%. The extent of the chelate effect depended upon whether EDTA was present in the Ni solution before or after contact with soil.
