Heavy metals distribution in different parts of cultivated and native plants and their relationship with soil content

Abstract

In semiarid region of Irece, state of Bahia, Brazil, there are superficial elongated strips in form of lateritic crust derived from hydrothermal weathering of sulfide known as “gossans” with heavy metals anomalies. Thus, this study aimed to evaluate the presence and concentration of metals As, Cd, Pb, Cu, Cr, Fe, Mn, Ni, Ti, and Zn in different parts of cultivated and native plants in “gossan” area and relationship with soil content, in an area that has been used for decades by small family farmers for the crops production and raising small animals. The metals were analyzed by ICP-OES in plant and soil extracts obtained after acid digestion (USEPA SW-846 3050B). As, Cd, and Ni were not found in the evaluated plants. Pb, Fe and Ti concentrated in the roots of several plants, with emphasis on buffel grass (Pb and Fe) and corn and white pinion (both Fe and Ti). Zn and Mn were distributed in all parts of plants evaluated. Cu levels found were quite below of phytotoxic levels. Significant positive correlation between lead in root and soil and negative between lead in stem, leaf, and soil were observed, indicating a plant protection mechanism concentrating lead in the root without translocating it to the aerial part. Similar behavior has occurred in relation to Cu, concentrating it in the root and fruit. Fortunately for the farmers and consumers, the highest concentration of heavy metals was observed in the roots of both cultivated and native plants.