Ribeira de Águas Fortes’ biodiversity threatened by acid drainage

Ribeira de Águas Fortes’, a water course near Ajustrel’s mine. Aljustrel. (Alentejo, Portugal).

Acid drainage problems are common in pyrite mines. It’s formed when sulfuric minerals that were in deep areas are exposed to oxygen and water, reacting into sulphates (acid substances).

A group of students at Colégio Valsassina conduced an investigation, to Ribeira das Águas Fortes. After analyzing samples of a 1000m section of the water course no macro-invertebrates (bioindicators on the health of water courses) were found. If the BMWP’ index is applied, the final result would be 0. This result points out the severe contamination of Águas Fortes’ waters (Alba-Tercedor et al., 1988).

As vegetal biodiversity is concerned, the surrounding area of the water course under study was very scarce. Two species were dominant, Lavandula stoechase and Cistus ladanifer. This last one is a typically Mediterranean and well fitted to unfertile soils (Batista et al., 2012). Cistus ladanifer shows a great capacity to thrive on soils degraded by mining activity, with high concentrations of Lead. (Abreu et al., 2012).

Diogo Oliveira, Pedro Leal, Carolina Fonseca, Francisco Paim, Henrique Avelar, Vasco Diogo.

Colégio Valsassina. Portugal.

Alba-Tercedor, J. & Sánchez-Ortega, A. (1988). Un Método rápidp y simple para evaluar la calidad biológica de las águas corrientes basado en el de Hellawell (1978). Limnética, 4: 51-56 (1988). Asociación Española de Limnologia. Madrid. Spain.

Batista, M. J. ; Abreu, A. A ; Pinto, M. S. (2006) Contribuição do Cistus ladanifer L. para a atenuação dos efeitos da exploração em algumas minas da Faixa Piritosa Ibérica. Évora. [s.n.], 2006. il., 1 figura e 2 tabelas ; Sep. de: VII Congresso Nacional de Geologia : Livro de Resumos, II, 2006, p. 447-450.

Abreu, M.M.; Santo E.S.; Anjos C.; Magalhães M.C.F.; Nabais, C. (2012). Capacidade de absorção do chumbo por plantas do género Cistus espontâneas em ambientes mineiros. Revista de Ciências Agrárias. Disponível online em http://www.scielo.oces.mctes.pt/pdf/rca/v32n1/v32n1a16.pdf . consultado em 13/10/12.