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Heavy metal toxicity has become a global concern due to the ever-increasing contamination of soil, water and crops. Until recent decades little has been known about the remediation of mining sites using spontaneous plants in Latin America. Soil and plant samples were taken in Peru, at a polymetallic mine (mainly silver, lead and copper) in Cajamarca Province, Hualgayoc district. Top soils (0–20 cm) were analyzed for physical and chemical properties by standard methods. Total Pb and Zn concentrations in top soils were determined by ICP-OES. Similar metals in plants were analyzed separately (aerial and root system). Ti content was used as an indicator for contamination of plant samples with soil particles. Translocation Factor (TF) and Shoot Accumulation Factor (SAF) were determined to assess the tolerance strategies developed by these species and to evaluate their potential for phytoremediation purposes. The non polluted soils had near neutral pH (6.8 ± 0.1), a great content of organic carbon (42 ± 4.0 g kg − 1 ) and a silt loamy texture. According to the total metal concentrations, the polluted soils exceeded toxicity thresholds; large Pb (13,105 ± 3147 mg Pb kg − 1 ) and Zn (28,393 ± 3458 mg Zn kg − 1 ) concentrations were detected. Unusually elevated concentrations of these metals were detected in roots of Bidens triplinervia L. (e.g. up to 5180 mg Pb kg − 1 and 9900 mg Zn kg − 1 ) while Senecio sp. accumulated more heavy metals in shoots (e.g. up to 4250 mg Pb kg − 1 and 3870 mg Zn kg − 1 ). The TF values were B. triplinervia and > 1 in Senecio sp., while the SAF were B. triplinervia can be considered potentially useful for phytostabilization due to its capacity to restrict the accumulation of elevated amounts of Pb and Zn to the roots, while Senecio sp. could be utilized for phytoextraction technologies. Moreover, these plants showed an elevated transfer factor and grew in the presence of other toxic metals. The present study, to the best of our knowledge, is the first report on the metal accumulation in roots of B. triplinervia and provides a pioneer contribution to the very small volume of data available on the potential use of native plant species from contaminated sites in phytostabilization and phytoremediation technologies.

Metal mining gives access to very important resources but contributes to severe and diverse environmental problems. Until recently, little has been known about the remediation of mining sites in Latin America using metallophytes. The present study was designed to identify and characterize spontaneously growing heavy metal tolerant plant species in the area around the polymetallic Carolina mine in Hualgayoc (Cajamarca, Peru). The aim was to find species that are potentially useful for phytoremediation. Plants and soils were sampled and analysed for concentrations of As, Fe, Mn, Pb, Zn and Ti. The Translocation Factor (TF) and the Bioaccumulation Factor (BF) were determined and used to measure the amount of each element accumulated in shoots and roots of each plant species. The top soil had a neutral pH (7.4 ± 0.5), an organic carbon content of 24 ± 11 g kg− 1 and a loam texture. According to the total metal concentrations, all samples exceeded soil toxicity thresholds. Indeed, high Pb (from 120 to 111,290 mg kg− 1) and Zn (from 380 to 46,500 mg kg− 1) concentrations were detected in all soil samples. In plants, great Pb and Zn concentrations were found in the shoots of Plantago orbignyana Steinheil (from 6070 to 8240 mg Pb kg− 1 and from 8290 to 11,560 mg Zn kg− 1), Lepidium bipinnatifidum Desv. (from 6300 to 7240 mg Pb kg− 1 and from 4610 to 5370 mg Zn kg− 1), Baccharis latifolia Ruiz & Pav Pers. (from 2120 to 3060 mg Pb kg− 1 and from 1090 to 1490 mg Zn kg− 1), and Sonchus oleraceus L. (from 2180 to 2900 mg Pb kg− 1 and from 1340 to 1910 mg Zn kg− 1). The great TFs indicate that these plant species effectively translocate metals. L. bipinnatifidum shows the greatest TF values (i.e., 143 for Pb and 21.5 for Zn). These species could have potential for phytoextraction due to their large capacity to uptake and transfer elements, and their ability to grow in the presence of other toxic metals. To the best of our knowledge, the present study is the first report describing the metal accumulation ability of these plant species.