Heavy Metals and Nutrients Uptake by Medicinal Plants Cultivated on Multi-metal Contaminated Soil Samples from an Abandoned Gold Ore Processing Site

Abstract

Heavy metal extraction from soils is one of the functions of plants which is widely studied and applied worldwide. However, little is known to what extent medicinal plants can accumulate these metals and cause problems to human health. This study aimed to evaluate the accumulation of heavy metal/loid in plant tissues, nutritional imbalance, and the effect of heavy metal concentrations in soil on the medicinal plants. The experiment was conducted in a factorial scheme with three contaminated soil samples and a soil sample from an uncontaminated field and three medicinal species: Cynara scolymus, Ocimum basilicum, and Rosmarinus officinalis. The heavy metal content in the biomass increased with increasing soil samples concentration. Biomass production, nutritional imbalance by nutrients did not show consistent results according to soil contamination criteria and are not good indicators of heavy metals presence in plant tissues, since they did not allow predicting the presence of metal in the plants, due to the different behavior of elements and plant species. There was a high concentration of Cd, Cr, Pb, and As and micronutrients Fe, Zn, and Cu in the plant tissues, above the limits recommended by the World Health Organization. Therefore, as the components of C. scolymus, O. basilicum, and R. officinaliss are used to prepare teas, condiments, or consumed raw, coupled with the ability of such species to concentrate toxic metals, the continued use of these plant products containing these metals can pose a potential health concern.