Mercury accumulator plants with phytoremediation potential in a region of northwestern Colombia

Mercury (Hg) is a toxic and nonessential metal for living organisms, and its environmental contamination poses a global concern. Gold mining is one of the primary sectors responsible for mercury emissions, which contributes significantly to ecosystem pollution. In this study, the natural regeneration of vegetation was evaluated at seven mining sites with varying periods of inactivity, and the accumulation of mercury in plant species was analyzed. Random plots were established at each site, where species were identified and selected to determine mercury concentrations in their tissues and calculate bioconcentration (BCF), translocation (TF), and accumulation (AF) factors. A total of 2505 individuals were identified from 46 species and 20 families, with a predominance of herbaceous species. The most widely distributed species, found at more than four study sites, included Homolepis aturensis, Andropogon bicornis, Clidemia capitellata, Tonina fluviatilis, Pityrogramma calomelanos, Cespedesia spathulata, and Fuirena robusta. The total mercury (THg) concentrations varied, ranging from 29.0 to ~ 21,500 ng g^-1 in soils, < 20.0 to ~ 11,000 ng g^-1 in roots, and < 20.0 to ~ 6500 ng g^-1 in shoots. The BCF, TF, and AF values ranged from 0.14 to 1.96, 0.16 to 5.3, and 0.12 to 4.45, respectively. However, TF values may lack precision, as mercury in shoots could result from both translocation from roots and atmospheric deposition. Miconia reducens, Cecropia peltata, and Pityrogramma calomelanos presented the highest BCF values, indicating their potential for phytoremediation of mercury-contaminated soils in areas affected by gold mining.