Bioacumulação, tolerância e fitoestabilização de cobre por Tridax procumbens L. (asteraceae)

Abstract

Several metals can trigger contamination in the soil resulting from human activities, such as industrial and agricultural processes, and can reach toxic levels and cause damage to plant development, damage to the environment and human health. Numerous studies have shown that certain plants are tolerant to the condition of cultivation in soil with an excess of metals and have potential for phytoremediation, a technology that can be defined as the application of plants for the remediation of a contaminated environment. In this context, the objective of this work is to evaluate the phytoremediation potential of Tridax procumbens, through analysis of tolerance, bioaccumulation and distribution of Cu in this species. For this, T. procumbens plants were cultivated in nutrient solution and in soil containing excess of the metal in different concentrations. At the end of the cultivation period, the Cu absorbed by the plants and the remainder in the soil were determined using the flame atomic absorption spectrometry technique. Phytoremediation indices were calculated, such as bioaccumulation factor (BCF), translocation factor (TF), tolerance index (TI) and metal extraction rate (MER). The plants developed some symptoms of toxicity, reduced phytomass, and low tolerance in higher concentration treatments, especially in hydroponics. The TF, in both crops, and the soil MER showed that the species under investigation is not indicated for Cu phytoextraction. However, there was a high accumulation of metal in the roots, which, together with the low translocation to the shoot, revealed the potential of planting T. procumbens for phytostabilization of Cu-contaminated soils, a phytoremediation mechanism that provides a reduction in the mobility of the contaminant and, consequently, minimizes environmental risks.