Evaluation of the potential of Mimosa pudica for phytoremediation of mining waste soils contaminated with zinc and copper, in the years 2014 and 2019

Abstract

As an alternative solution to the problem of heavy metal contamination in mining waste, this article evaluates the capacity of Mimosa pudica, a native plant of the central region of Nicaragua, to phytoremediate soils contaminated by zinc and copper, from artisanal mining sites in the municipality of Santo Domingo, department of Chontales. The sites were: Plantel La Estrella, evaluated in 2014 on two dates; and Rastra Adonis and Rigoberto Miranda, evaluated in 2019. Plant and rhizosphere soil samples were collected to quantify physicochemical parameters and to determine the concentration of metals of interest. Total metals were determined using the ICP-OES technique and the results for Plantel La Estrella (II Sampling) showed zinc concentrations between 177,756 mg/kg and 437,873 mg/kg, below the maximum permissible value established in the Canadian Guide. However, Plantel La Estrella (I Sampling), Rastra Adonis and Rigoberto Miranda showed values ​​higher than the compared value. For copper, concentrations ranging from 116,273 mg/kg to 252,815 mg/kg were observed at all sites, exceeding the maximum limit established by regulations. When evaluating zinc and copper concentrations, bioaccumulation and translocation were determined in vegetative organs such as roots, stems, leaves, seeds, and flowers, with bioaccumulation and translocation factors greater than one. This demonstrates that the plant has the capacity to tolerate and bioaccumulate these metals, making it suitable for phytoremediation of these soils.