Arsenic and heavy metals in native plants at tailings impoundments in Queretaro, Mexico

Ten native plants species that grow in three tailings dams from Ag, Pb, Cu and Zn mine in Queretaro, Mexico were studied. Total concentrations in tailings were 183-14,660. mg/kg. As, 45-308. mg/kg. Cd, 327-1754. mg/kg. Pb, 149-459. mg/kg. Cu and 448-505. mg/kg. Zn. In the three tailings dams, the solubility of these elements is low. Tailings in dam 1 are acid generating while tailings in dams 2 and 3 are not acid-generating potential. Plants species that accumulate arsenic and heavy metals was identified; Nicotina glauca generally presented the highest concentrations (92. mg/kg. As, 106. mg/kg. Cd, 189. mg/kg. Pb, 95. mg/kg. Cu and 1985. mg/kg. Zn). Other species that accumulate these elements are Flaveria pubescens, Tecoma stans, Prosopis Sp, Casuarina Sp and Maurandia antirrhiniflora. Two species were found that accumulates a large amount of metals in the root, Cenchrus ciliaris and Opuntia lasiacantha. Concentrations in soils in which plants grow were 488-5990. mg/kg. As, 5-129. mg/kg. Cd, 169-3638. mg/kg. Pb, 159-1254. mg/kg. Cu and 1431-13,488. mg/kg. Zn. The Accumulation Factor (AF) determined for plants was less than 1, with exception of N. glauca for Cd. The correlation between arsenic and heavy metals found in soils and plants was low. Knowledge of plant characteristics allows it use in planning the reforestation of tailings dams in controlled manner. This will reduce the risk of potentially toxic elements are integrated into the food chain of animal species.