S3: Borralha (Montalegre, PT)


Site “S-3”, Location: Borralha Mine, Salto, Montalegre, Vila Real District, Portugal 41º 39’ 25.18’’ N 7º59’ 05.19’’ W

Brief description:

The Borralha mine (60 km NE from Porto) born in 1902, was composed by 52 concessions [28 (W); 12 (W, Sn); 10 (Sn) and 2 (W, Cu, Ag, Mo)]. The economic exploitation was mainly focused on wolframite, scheelite and chalcopyrite. In 1986 the mine closed, without surveillance, being the sources of contamination the tailings (Figures A, C, D), with huge volumes, and the pond (Figure B) with rejected muds and slush discharged from the ore process. This accumulation of “sterile” from the exploitation and ore treatment is widespread throughout the mining area promoting the formation and drain of acidic waters.

Some of the contaminated soils in this area will be used for the production of energetic cultures, sunflower (Helianthus annuus) and poplar (Populus sp.). Microorganisms such as mychorrizal fungi and plant-growth-promoting bacteria will be inoculated in the plants to foster their establishment and the recovery of soil functions.
At the moment the project is at the initial state. The soil samples for chemical and physical characterization were collected and the plots are under implementation.

The use of such sites to establish plants that can be used as biomass for energetic purposes can provide an economic added value. The vegetation cover helps mitigating the problem of disseminating the pollutants through the different environmental compartments and promotes the recovery of the ecosystem soil functions through time.