Spontaneous growth of plants enhances phytoextraction on abandoned coal mine wastes in Central Alborz coalfield, Iran.

Abstract

Coal mining disperses heavy metals into the environment, necessitating the identification of metal-tolerant plants for ecosystem restoration. This study evaluated the phytoremediation potential of plant species in abandoned coal wastes in northern Iran. Pollution indices indicated moderate contamination of Cu, Ni, V, Zn, Pb, Cr, and As in coal wastes. The plants varied in their ability to accumulate and translocate these metals, with most showing efficient root-to-shoot translocation. Artemisia scoparia (41.06 mg.kg^-1) and Capparis spinosa (42.48 mg.kg^-1) were effective for Cu phytoextraction. Most species, notably Cynodon dactylon (3.4 mg.kg^-1), showed promise for phytoextraction of Cr. Capparis spinosa (7.67 mg.kg^-1) exhibited potential for Pb phytoextraction. Most plants, particularly Hordeum vulgare and Melica persica, were effective phytoextractors of Ni. Sylibum marianum accumulated V beyond phytotoxic levels. Chenopodium album and Glaucium fimbriligerum were identified as phytoextractors of Zn while Cynodon dactylon and Hordeum vulgare, accumulating >100 mg.kg^-1 Zn in roots, showed potential for phytostabilization. Sylibum marianum and Glaucium fimbriligerum, acted as excluders for As. Kochia prostrata and Artemisia aucheri were excluders for Cu, Cr, Ni, and Pb. This study provided the role of multiple indigenous plants, including perennials and annuals with diverse life forms, in metal extraction and stabilization for sustainable coal waste management.