Tolerance to metals in two species of fabaceae grown in riverbank sediments polluted with chromium, copper, and lead

Abstract

Matanza-Riachuelo river is the most polluted river in Argentina and one of the most pollute drivers in the world. Among the pollutants in the riverbank sediments, metals can be found in toxic concentrations to biota. During 2015, a pilot-scale rehabilitation was carried out in a selected section of the riverbank located in the lower basin of the river, which consisted of the reintroduction of several native plant species, including Erythrina crista-galli and Senna corymbosa (Fabaceae). In order to evaluate the tolerance of these species to polluted sediments and quantify the bioaccumulation of Cr, Cu, and Pb in aerial tissues and roots, a 153-day trial was carried out using seedlings of both species cultivated from seeds. It was found that both species showed good growth in riverbank sediments polluted with metals. None of the species has accumulated significant amounts of Cr, Cu, or Pb, and the translocation of Pb from the roots to the aerial tissues has been observed only in the case of E. crista-galli after 5 months of planting. However, the concentration of this metal in the aerial biomass was low. Individuals of both species planted in the riverbank showed tolerance not only to the contaminants present in the sediments but also to the environmental stress of the riverbank.