Analysis of heavy metals in silvopastoral systems: a strategy for livestock sustainability in the district of Molinopampa, Amazonas, Peru

Heavy metal contamination poses a latent threat to the sustainability of silvopastoral systems and animal health. This study evaluated the concentrations of toxic metals—iron (Fe), copper (Cu), zinc (Zn), lead (Pb), cadmium (Cd), chromium (Cr), nickel (Ni), arsenic (As), and aluminum (Al)—in the soil, pastures, and trees of the small Molinopamba basin (Amazonas) by analyzing Root bioaccumulation (RB), foliar bioaccumulation (FB), and translocation factor (TF) to determine the risks of movement and accumulation in plant biomass. The results showed that most metals remained retained mainly in the soil, especially iron (Fe) (>2300 ppm) and lead (Pb) (up to 29.57 ppm), indicating limited transfer to plants. Zinc levels in grasslands were generally low; the highest value (30.25 ppm) was observed under the Pinus patula tree but remained within safe limits. Accumulation in roots exceeded accumulation in leaves in most species, especially in the case of iron and copper, and TF values were mostly less than one, indicating limited transfer to aerial organs. Erythrina edulis and Alnus acuminata showed favorable characteristics for plant fixation by limiting the transfer of metals to forage. These results provide fundamental evidence for the sustainable management of tropical silvopastoral systems, confirming the need to regularly monitor elements such as zinc and cadmium to prevent risks to livestock health and maintain food security in the Amazonas region.