Sustainable phytoremediation of highly acidic mine spoil through economical valuable crop Pelargonium graveolens L

Abstract

The phytostabilization of acid mine spoil by industrially important aromatic crops could be a sustainable solution with minimum input for the problem associated with acidic mine spoil-affected areas. In the present study, the suitability of Pelargonium graveolens for phytostabilization of acidic mine spoil has been investigated in three different combinations (T1: 100% soil; T2: 100% mine spoil, T3: 75 mine spoil: 25 soil and T4: 50 mine spoil: 50 soil). The plant growth performance, metal accumulation, ecological indices, soil properties, enzymes, and microbial diversity along with the identification of dominant bacterial isolates were investigated in the study. The results indicated that mine spoil was highly acidic (pH 3.01) and rich in minerals and toxic metals. The values of the tolerance index and oil content of P. graveolens L under different treatments varied from 43% to 89% and from 0.10 to 0.13% without affecting oil quality, respectively. Bioconcentration (BCF) and translocation factor (TF) indicated that the P. graveolens can be used as a phyto-excluder for Al, Fe, Cr, Zn, and Pb and phytoextractor for Cu, Ni, and Mn. The plantation of P. graveolens enhanced the microbial biomass and enzymatic activities of soil and immobilized the metals. The increase in the Shannon index from 1.67-1.86 to 1.9-2.61 suggested enhanced bacterial diversity after plantation. The identify bacterial isolates were metal tolerant and plant growth promoters. The study suggested that P. graveolens is suitable for the phytostabilization purpose of acidic mine spoils along with the economic return.