Radioecological investigations in Brazilian tropical plants

Abstract

The accumulation and long term behavior of radiocesium in chili pepper trees (Capsicum fructescens) were studied. The trees to be analyzed had been cultivated at one of the sites where the Goiânia radiological accident occurred and one of them transplanted to another site with uncontaminated soil. The aim of this paper is to examine the decline of 137 Cs as function of time and verify how this radionuclide and 40 K were distributed throughout this tropical plant in natural environmental conditions.

Varietal difference in radiocesium uptake and transfer from radiocesium deposited soils in the genusAmaranthus

“…Furthermore, although K, sodium (Na) and Cs are alkali metals and are assumed to act similarly, the distribution pattern of K in different plant organs is different from that of Cs, as K was more preferentially translocated to the shoot from the roots (Tsukada et al 2002;Carvalho et al 2005). The addition of K can reduce plant Cs uptake due to the chemical similarities between these elements (Bange and Overstreet 1960;Handley and Overstreet 1961;Shaw and Bell 1991;Hampton et al 2004;Isaure et al 2006), and K and Cs enter root cells via the same molecular mechanism(s) (reviewed by White and Broadly 2000).…”

Accumulation and long-term behavior of radiocaesium in tropical plants

“…Similarly to potassium, caesium has a high mobility within a plant, exhibiting the highest values of concentration in the growing parts of the tree: fruits, leaves, twigs, barks and the outer growth layers [1][2][3][4][5]. In this way, the results presented in Table 1 for the mean values of 137 Cs and 40 K concentrations in some compartments of tropical plants contaminated by caesium suggests that tissues with low K concentrations (on a dry weight basis) have also low Cs concentration.…”

“…In recent years, there has been a growing interest in the evaluation of nutrient fluxes and radioactive contaminants in forest and agricultural ecosystems [1][2][3][4][5]. For being chemically similar to available nutrients in soil (such as potassium), radiocaesium is absorbed by plants, entering the food chain and therefore representing a significant pathway of human radiation exposure.…”

Accumulation and long-term decline of radiocaesium contamination in tropical fruit trees

“…Technical details of sample preparation and analysis can be obtained in Refs. [1][2][3][4]. Concentrations of free NH 4 + ions were estimated using the phenol-hypochlorite colorimetric method for the same compartments of chili pepper tree samples [7].…”

“…In the study of nutrient fluxes in plants, the suitability of using radioactive contaminants as tracers is a complex question, which has guided several researches [1][2][3][4][5]. For being chemically similar to some available nutrients in soil (such as potassium or ammonium), radiocaesium is absorbed by plant roots, being transported to its various compartments.…”