USE OF SI-PHYTOLITHS IN DEPOLLUTION OF MINING AREAS IN THE CERRADO-CAATINGA REGION, MG, BRAZIL.

Abstract

Treating of metal contaminated areas became a very important problem with increasing industrial
and agricultural activities. Many of the used methods are very expensive, need intensive human interaction or
have a very negative influence on the cleaned regions. The use of Si-Phytoliths is a simple, low cost and a very
effective way to obtain good results in low contaminated or as the final process in highly contaminated places.
The method is based on the fact that plants produce Si-Phytoliths and trap significant quantities of heavy metals
in these amorphous to microcrystalline structures. The solubility of the Si-Phytoliths under tropical soil
conditions is lower than that of the heavy elements brought directly in the soil by wash-fall out, or by degrading
of organic parts of the plants on the surface. In this way, it is possible to retain liberation to the environment
from short to long periods and attend environmental laws and norms. Initial tests with different plants like
Ricinus comunis L., Andropogon arundinaceus Willd., Zea Mays L., Brachiaria sp. L. and Saccharum
officinarum L. planted on substrates with metal concentrations (Al, Fe, Mn, Ti, Zn, Cu, Pb, Cd, Ba, Hg, S) have
shown that the plants absorbed elements and quantities in the different parts like leaves, roots, stems, flowers and
fruits. This allows a selective use due to contamination varieties and a possible economic use of parts of the
plants and an effective planning of the decontamination conditions.