Bioaccumulation and translocation of Cu, Cd, Zn, and As in four native tree and shrub species growing on soils contaminated by an abandoned gold mine

Abstract

Plants are known to have the ability to bioaccumulate metal(loid)s in tissues andtranslocate them from roots to aerial biomass. Native plants grow in soil contaminatedwith mining waste in the town of La Planta (Caucete, San Juan, Argentina). Theobjective of this study was to evaluate the bioaccumulation and translocation capacityof Cu, Cd, Zn and As in Prosopis flexuosa (Pf), Larrea cuneifolia (Lc), Bulnesia retama(Br), and Plectrocarpa tetracantha (Pt) that grow in contaminated soil. Organ samples(leaf, branches, stem, bark and root) of 3 plants per species (n=12) were collected.Rhizospheric soil samples around each tree and shrub were taken from the first 20 cmof depth (n=12). Concentrations of metal(loid)s in organs and soil were determined.Samples were digested with a combination of HNO 3 , H 2 O 2 and HF, and quantificationswere made using ICP-MS. Bioaccumulation Factor (BAF) and Translocation Factor(TF) were calculated. Results showed that the most concentrated metal(loid)s in Lc, Pfand Br were Cu and Zn, and in Pt were Zn, Cu and As (p<0.001). BAF and TF values​​greater than 1 were obtained for the four species, indicating that these species arebioaccumulators. The highest BAF values was obtained for​ Cu in the four species(p<0.001). Regarding TF, higher values of Zn were only observed​ in leaf of Lc(p<0.001). The high concentrations of metal(loid)s measured in plant organs of thefour native species plus the values ​​of BAF and TF indicate a high potential forphytoextraction. Comparing bioaccumulation capacities, Pt>Pf>Lc for As,Pf>Lc>Pt>Br for Cu, Pf>Pt>Lc>Br for Zn, and only Pt was effective for Cd.Bioaccumulation capacity of Cu, Cd, Zn and As found in the native plants studied inthis work, generates baseline information for the implementation of phytoremediationstrategies. These species present anatomical, morphological and structural adaptationsthat allow them to survive adverse climatic conditions that characterize arid and semi-arid environments. This would avoid the use of exotic species that could generatedisturbances in the polluted environment and a higher economic cost.