Arsenic Speciation in Plant Samples from the Iron Quadrangle, Minas Gerais, Brazil

Abstract.

Several plants, especially ferns, have been shown to tolerate and accumulate high arsenic concentrations in soils. The leaves and roots of the ferns Pteris vittata (Chinese brake) and Pityrogramma calomelanos as well as a medical plant (Baccharis trimera) were sampled together with their associated soils in a region impacted by ore mining, the Iron Quadrangle in Brazil, where arsenic concentrations in the soils vary sharply (6–900 µg g⁻¹). The bioaccumulation factors were found to be low compared to the literature data, which can be explained by the low water-soluble fraction of arsenic in soil. The arsenic species in the plants were mainly arsenite. In comparison to the rhizoid samples, the concentrations of arsenic were higher in the leaves of the fern samples. The medical plant behaved differently. The bioaccumulation factor was low (0.7), and trimethylarsine oxide was detected as the third arsenic species beside arsenite and arsenate in both the roots and the leaves.