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(432) Water quality and toxicity assessment of a mine effluent: Short-term laboratory and in situ biotests with invertebrates, fish and macrophytes. Gerhardt, Almut1, Janssens de Bisthoven, Luc1, Guhr, K.1, Soares, A.2, 1 2 ABSTRACT- S. Domingos mining area (Portugal), one of the largest abandoned mines in Europe, still causes heavy pollution due to acidification and heavy metals. The hydrological basin consists of lotic and lentic freshwater systems with a natural pH and metal gradient. To assess water quality and toxicity a TRIAD approach was chosen, consisting of 1) biological assessment and community analysis of benthos samples and deformities in chironomids, 2) monthly chemical analyses of the surface water in the natural pH and metal gradient (As, Cd, Cu, Co, Fe, Mn, Pb, Zn, K, Na, Ca, Mg, Cl, S) and sediment characterisation and 3) short-term toxicity assays (48h) in the laboratory and in situ with standard reference organisms such as Daphnia, Tetrahymena thermophilus (Protoxkit FTM), Chironomus gr. plumosus and the macrophyte Lemna gibba and with locally important species such as Gambusia holbrooki, Atyaephyra desmarestii and Leptophlebiidae. Survival and different types of behaviour (locomotion, ventilation) were recorded online with the Multispecies Freshwater Biomonitor (LimCo International). Other test endpoints were chlorosis, necrosis and growth for L. gibba and feeding inhibition for T. thermophilus. Total metal concentrations in the test organisms were determined and related to those in the water. Increasing metal concentrations in the water at low pH induced higher mortality and stress behaviour. Comparisons of inter-species sensitivities and response times and validation of laboratory results in the field will be discussed. Key words: TRIAD, metal toxicity, acidification, online biomonitoring |
