Trace elements tolerance, accumulation and translocation in Cistus populifolius, Cistus salviifolius and their hybrid growing in polymetallic contaminated mine areas

Abstract

Plants from Cistus genus show a great plasticity and are able to grow both in contaminated and non-contaminated soils. Cistus salviifolius L. was identified in several mines from Portuguese Iberian Pyrite Belt (PIPB) while Cistus populifolius L. was collected in 2009 in Chança and Caveira mines for the first time. In these mine areas, a hybrid of both species Cistus×hybridus Pourr. was also collected being this its first report from those areas. This study aimed to compare the biogeochemical behavior of the three Cistus species growing in the polymetallic mine areas of Caveira, Chança and São Domingos (PIPB). Their possible use in phytoremediation programs of multielemental contaminated soils was evaluated.Soils from Caveira and São Domingos presented high concentrations of various chemical elements and were considered seriously contaminated with As (13–3030mg/kg), Cu (159–1750mg/kg), Pb (932–9210mg/kg) and Sb (23–486mg/kg), and with severe contamination of Zn (33–1010mg/kg). Chança soils presented the lowest trace elements contamination.The three species showed tolerance to moderate acid soils (4.2<pH<6.1), with low fertility and high multielemental contamination. Cistus×hybridus, C. populifolius and C. salviifolius growing in the same mine area are not significantly different for elemental concentration, except for Fe and Sb. Similar behavior was observed for C. populifolius and hybrid growing in different mine areas (Caveira and Chança). Besides the different concentration of each chemical element in Cistus plants, no significant differences were observed in the translocation capacity from roots to shoots for all species: non essential elements and Fe were stored in roots (translocation coefficient: 0.1–0.9) and macro- and micronutrients were transported to the aerial part (translocation coefficient: 1.0–7.7) due to their metabolic functions.All Cistus populations can be considered Mn accumulators, and non-accumulators of As, Cu, Fe, Pb and Sb as well as Caveira plants for Zn (soil-plant transfer coefficient <1). Chança and São Domingos plant populations showed both, accumulators and non-accumulators behavior for Zn. The studied plant species did not show significant ecological variability intra or inter-population and can contribute to the rehabilitation of mining areas with semiarid characteristics.