Analysis of the Use of Sorghum in Phytoremediation Processes Involving Gold Mining Waste in the Municipality of Marmato

Abstract

A study was conducted focusing on the capacity of sorghum to accumulate cyanide molecules in contaminated soils—cyanide being a compound that enables gold dissolution in water and is highly toxic if ingested. Cyanide is found in large quantities in watercourses such as the La Cascabel Stream in the municipality of Marmato, and in smaller amounts in adjacent soils due to the molecule's natural degradation; even in small quantities, however, it causes soil phytotoxicity for most plants. In situ tests were carried out, taking into account that the cyanide molecule is more stable in an aqueous medium; mining residues—such as cyanide-contaminated sands—are discharged into watercourses, transported, and deposited on floodplains through fluvial processes, contributing to a significant increase in heavy metals and toxic components and resulting in soil degradation. The study quantified the use of phytoremediation for soil decontamination and assessed the plants' capacity to absorb organic and inorganic contaminants, presenting comparative data between plants grown in non-cyanide-contaminated soil and those grown in soil containing mining residues and subjected to cyanide-laden irrigation.