Behaviour of Coincya transtagana (Cout.) Clem.-Muñoz & Herm.-Berm., an Iberian endemism in the area of the abandoned mine of Aparis

The rare endemic species Coincya transtagana (Cout.) Clem.-Muñoz & Herm.-Berm (Brassicaceae) is distributed in the southwest of the Iberian Peninsula, in Alentejo, Algarve and Andalusia. This species has a strong association with copper mining areas in Baixo Alentejo, including the Aparis mine, in Barrancos. However, it is still unknown if this species is an indicator of metals in the soil (metallophyte). This study aims to investigate the behavior of this species in soils rich in potentially toxic elements. To this end, soil samples and plants were collected in the Aparis mine, and soils’ physicochemical and multi-elemental characterization, and enzymatic activities (dehydrogenase, β-glucosidase, cellulase, acid phosphatase, urease, and protease) were evaluated. Plant biomass was determined, and plants’ chemical multielemental analysis was carried out. The results showed that the soils had slightly basic pH values and not saline, poor in mineral N, with medium to high organic matter concentration, low C:N ratio, medium cationic exchange capacity, and normal Fe, Mn, and Ca concentration. In the soils, the concentration of Zn and Cu was above, and K and Mg were below the values favorable to the good plant development. Dehydrogenase had the highest enzymatic activity whereas protease had the lowest activity. The samples in which C. transtagana had higher biomass corresponded to soil samples where the soil has higher quality. Among the potentially toxic chemical elements studied, Cu is the element with the highest concentration in both soils and plants. The plants present accumulative and non-accumulative behaviors, being considered an accumulator of Mo and S, as well as tolerant to the elements Ni and Zn. In conclusion, our findings showed that this species is well adapted to the mine soil, regardless of the contamination at the local. Further studies are required to test the potential of C. transtagana for potentially toxic soil elements phytostabilization.