VEGETATIVE COVER OF A MINE TAILINGS WITH BERMUDA GRASS (Cynodon dactylon L.) TO MITIGATE POLLUTION

Abstract

The vegetative cover of mine tailings with grasses has environmental benefits and positive impacts on public health by improving air and water quality, as well as the overall well-being of surrounding communities. This study evaluated the ability of Cynodon dactylon L. grass in the cover of a mine tailing using three doses of vermicompost (Vlow [60 Mg ha-1], Vmedium [80 Mg ha-1], and Vhigh [100 Mg ha-1]) to improve the conditions of the site, which was physically and chemically characterized. The concentrations of lead (Pb), cadmium (Cd), nickel (Ni), and zinc (Zn) were determined before and during the experiment. Ninety-six and 202 days after planting (dap), grass was harvested to determine the concentrations of the potentially toxic elements (PTE) in the root and aerial sections. The production of dry matter and the growth of the grass were evaluated. Results showed that, before the experiment was established, the tailing had a low concentration of organic matter. After incorporating the vermicompost, an increase was observed in the concentrations of phosphorous (P), potassium (K), calcium (Ca), and magnesium (Mg). Ninety-six days after planting, in the treatment with the low dose of vermicompost, C. dactylon absorbed 202.13 mg Pb kg-1, 37.26 mg Ni kg-1, and 164.82 mg Zn kg-1 in its roots. Also at 96 dap, the highest PTE concentrations were found in the treatments with the highest dose of vermicompost. The greatest production of dry matter (231.55 kg ha-1 at 96 dap) and growth of the grass (9.7 cm, 73 dap) occurred in the treatment with the high dose of vermicompost, which highlights its efficiency in favoring its development and improving the conditions of the tailing. The absorption of the PTE by the grass highlights its contribution towards the reduction of dispersion and runoff of particles from tailings.