Solubility of lead, zinc and copper added to mineral soils.

Publisher Summary The zinc (Zn) content of soils, according to rather extensive surveys, is generally in the range of 10-300 ppm. Certainly Zn, because of its concentration, can be considered as a trace element in soil. It occurs most frequently in the lithosphere as the mineral ZnS (sphalerite). Zn appears to be scattered throughout the mineral fraction of soils. It is probably held in crystal lattices, by isomorphous substitution and as occluded ions. Since it is a trace element, it is usually surrounded, by many other solid phases. Zn can also be held, by exchange sites, and adsorbed to solid surfaces. Crops differ in their sensitivity to zinc deficiency. Zn deficiencies are frequently found on soils, with restricted root zones. The movement of Zn to plant roots is dependent on the intensity factors (concentration) and on the capacity factors (ability to replenish). Increasing the pH decreases the solubility of zinc in soils, and thereby reduces the concentration, the concentration gradient, and, hence, the uptake and availability of Zn to plants. Zn plays an important role in auxin formation and in other enzyme systems. Presently, Zn is recognized as an essential component in several dehydrogenases, proteinases, and peptidases.

Zinc in soils and plant nutrition

Publisher Summary This chapter presents exchange studies concerned with pure systems—namely, the suspensions of clay minerals obtained from known sources and the clay fraction of soils known to contain predominantly a particular clay mineral. Partly because of its high exchange capacity, montmorillonite plays a major role in obtaining information about the mechanism of cation adsorption, covering almost complete ranges of composition for different ion pairs. The clay minerals vermiculite, kaolinite and illite (hydrous mica) have been used less frequently. The information about cation exchange involving the organic fraction of soils is scarce because of the difficulties of isolation and identification. In some cases, organic soils (peat soils) have been used. Cation-exchange properties of soil-borne oxides have recently received attention because of the increasing interest in the adsorption of heavy metals. Apart from investigations on specific soil constituents, samples of natural soils have also been used to obtain an estimate of the expected behavior in a field.

Chapter 5: Survey of Experimental Information on Cation Exchange in Soil Systems

Adsorption—desorption and/or precipitation—dissolution processes of zinc in soils

Sorption of Zn, Cd and Cr on calcite. Application to purification of industrial wastewaters

Zinc adsorption by calcareous soils , Zinc adsorption by calcareous soils , مرکز فناوری اطلاعات و اطلاع رسانی کشاورزی

H. L. Bohn

Papers

Zinc Adsorption by Calcareous Soils