Assessment of the Use of Natural Materials for the Remediation of Cadmium Soil Contamination.

Rice plants accumulate cadmium (Cd2+) within the grain, increasing the danger of human exposure. Natural materials have been used in soil remediation, but few studies have examined the risks (based on the bioavailability of these metals to plants) of using these materials, so the practice remains controversial. In the present study, we evaluated the effectiveness of biochar produced from sugarcane bagasse, vermicompost (VC), vermicompost solid residue (VCR) and humin for remediation of Cd2+-contaminated soils. We characterized the interactions between these materials and Cd2+ and evaluated their capacity to alter Cd2+ availability to rice plants. Our results show that under the conditions in this study, biochar and humin were not effective for soil remediation. Although biochar had high Cd2+ retention, it was associated with high Cd2+ bioavailability and increased Cd2+ accumulation in rice plants. VC and VCR had high Cd2+ retention capacity as well as low Cd2+ availability to plants. These characteristics were especially notable for VCR, which was most effective for soil remediation. The results of our study demonstrate that in the tested materials, the bioavailability of Cd2+ to plants is related to their structural characteristics, which in turn determine their retention of Cd2+

Algunos atributos de la autonomía universitaria en la Argentina, Brasil y México: otra vuelta de tuerca

Este artículo reflexiona sobre la idea de autonomía universitaria y pone en relieve su construcción social y sus múltiples dimensiones históricas, epistemológicas y políticas. Asimismo, ilustra el contexto y las formas en que se manifiesta hoy en la Argentina, Brasil y México, según sus principales actores académicos. Se construyeron algunos indicadores empíricos que buscan capturar, al menos liminarmente, la complejidad de la noción. Los tres países ilustran cómo se configuran en ellos la autonomía, heredera de sus tradiciones culturales y conformada también por el desarrollo autopoiético de sus sistemas educativos

Sizes of Plants Grown on Substrates Containing Cd²⁺ 28 days after Seedling Transfer (DAT); bar is 50 mm.

<p>Sizes of Plants Grown on Substrates Containing Cd²⁺ 28 days after Seedling Transfer (DAT); bar is 50 mm.</p

Root and Leaf Growth Parameters for Plants Grown in Different Substrates Containing Retained Cd²⁺ from the First Harvest until 28 Days after Seedling Transference (DAT); on the x axis, 1st, 2nd, 3rd and 4th, respectively, indicate the first, second, third and fourth harvests from each experiment, conducted at seven-day intervals.

<p>Values are reported as averages ± the standard error (<i>n = 30</i>).</p

Adsorption parameters obtained from Freundlich and Langmuir isotherms.

<p>Adsorption parameters obtained from Freundlich and Langmuir isotherms.</p