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(80-37) Chemical and biological water quality assessment in S. Domingos mine (Portugal). Gerhardt, A.*,1,2, Janssens de Bisthoven, L.1,2, Guhr, K.1,2, Soares, A.2, 1 LimCo International, Ibbenbueren, Germany2 University of Aveiro, Aveiro, Portugal ABSTRACT- S. Domingos mine, abandoned for more than 30 years, is still cause of severe metal and acid pollution and may even affect water quality of the Chanca river and reservoir. In 2000 and 2001 two sampling campaigns have been performed along the acid mine drainage gradient at the confluence with the Mosteirao stream, which flows into the Rio Chanca upstreams of the reservoir. Rio Vascao, in an unpolluted catchment south of the mining belt and a site at the Rio Chanca upstreams of the mining belt at the border to Spain were chosen as reference sites. Additionally, a small reservoir collecting surface runnoff from the surroundings of the mine was studied. Benthic macroinvertebrates were collected according to standard rapid bioassessment methods. Simultaneously the following elements were measured in the water: metals: As, Cd, Co, Cr, Cu, Fe, Mn, Pb and Zn, other elements: Ca, K, Mg, Na, Cl and S. Seasonal changes in chemical composition and quantity of the water due to summer drought and episodic floods are disturbance factors, encouraging species with wide tolerance ranges. Rio Vascao clearly showed the best water quality, concerning taxa richness, %EPT-taxa, a high BBI (9), high preseence of scrapers, acid sensitive bioindicator species and saproby class I and II indicators. Water quality decreased as pH decreased and metal concentrations increased. This was clearly indicated by decreasing BBI, taxa richness, taxa composition (no Ephemeroptera, Crustacea and Mollusca at pH 3.3) and shift in FFG to predator dominance. Key words: bioassessment, biomonitoring, AMD, metal pollution |
