Abstract

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 gkg(-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. (C) 2011 Elsevier B.V. All rights reserved.