Roy Overstreet

On the Soil Chemistry of Cesium 137

The nonexchangeable fixation of macro amounts of cesium in five soils appeared to be different in character from the corresponding fixation of potassium and ammonium. It was also concluded that the fixation of cesium-137 in soils in carrier-free amounts is an essentially different process from those predominant in the fixation of macro amounts of cesium, potassium, and ammonium. Experimental procedures are described and results are discussed. (C.H.)

Divalent cations and the permeability to Na of the root meristem ofZea Mays

SummaryCa and Sr markedly inhibit the non-metabolic uptake of Na by the nonvacuolated tissue of maize root tips. Loss of previously absorbed Na is also reduced greatly in the presence of these ions. The results obtained suggest that in the absence of metabolically mediated ion transport the plasmalemma, stabilized by Ca-ions, is normally almost impermeable to Na and perhaps other ions. Ca appears to be slightly more effective than Sr in this regard.

Sodium Chloride, Calcium Chloride, and the Respiration of Maize Root Sections

The effects of sodium chloride and calcium chloride at concentrations of 0.005N and 0.010N upon the respiration of vacuolated and nonvacuolated portions of the root tip of maize have been investigated. In both sections CaCl2 produced marked stimulation, while NaCl had no effect. In this tissue stimulation of respiration does not appear to be directly related to metabolic ion accumulation.

Translocation of carrier-free 85Sr applied to the foliage of woody plants*

Abstract Carrier-free 85Sr was applied to the foliage of three genera of woody forage plants (Ceanothus, Adenostoma and Quercus) and subsequent translocation into untreated portions of the plants was measured. Experiments were conducted in the field and in the greenhouse. In all cases the bulk of the retained dose remained with the directly treated material. However, substantial concentrations of 85Sr were found in the new growth arising on previously treated branches of Ceanothus and Adenostoma. The amounts translocated under field conditions under which plants were subject to periodic wetting and drying were greater than those translocated by plants in the greenhouse.

The Behavior of Radioactive Fallout in Soils and Plants

The sequence of events involved in the transfer of radioisotopes from fallout to the tissues of mand through the food chain are reviewed. Topics discussed include the reactions of radioisotopes with soil; the uptake, translocation, and distribution of radioisotopes in plants; external and internal effects of radiation on plants; soil-plant relations; and the effect of soil management on the uptake of radioisotopes by plants. Emphasis is placed on the path of Cs/sup 137/ and Sr/sup 90/ through the food chain. (142 references.) (C.H.)