HP9 Environmental Assessment, Environmental Toxicology
D137-140
1:20 PM - 5:20 PM, Thursday
() Integrated biological and toxicological assessment of an Acid Mine Drainage gradient in Portugal.
Gerhardt, A1, Janssens de Bisthoven, L1, Soares, A1, 1 Dept. of Biology, University of Aveiro, Aveiro, Portugal, Portugal
ABSTRACT- A TRIAD-based integrated environmental assessment of an Acid Mine Drainage (AMD) gradient in the abandoned Sao Domingos Mine (Portugal) consisted of 1) chemical monitoring of total metal levels in the water in different seasons, 2) rapid bioassessment methods for benthic macroinvertebrates (Diversity Index (H), Belgian Biotic Index (BBI), Biomonitoring Working Party Average Score per Taxon (BMWP-ASPT) adapted to Spain, South African Scoring System (SASS4), Ephemeropter and Trichoptera taxa (ET-taxa %), Functional Feeding Groups (FFG, %) and functional trait diversity. 3) Toxicological assessment consisted of laboratory and in situ short term toxicity tests (48 h) with AMD water and acidified reference water using the Multispecies Freshwater Biomonitor (MFB) with Daphnia magna as standard test species and with field populations from locally abundant and ecologically relevant species (Atyaephyra desmaresti and Gambusia holbrooki). Survival and behaviour (locomotion, ventilation) were recorded on-line, and LC50, LT50 as well as 3d-response surface models were fitted. For behavioural early warning responses, the Lowest Observed Response Time (LORT) was defined. The sites in the AMD gradient were well discriminated by factor analysis of metals in the water, BMWP-ASTP, ET-taxa, Hemiptera (%) and Coleptera (%) and predators (%). Metal body burdens of the test species increased with decreasing pH, except at pH 3. LC50-48h analysis revealed AMD to be more toxic than acid stress, Daphnia magna being most sensitive, followed by Atyaephyra desmaresti and Gambusia holbrooki. Behavioural responses to AMD and acid stress followed the Stepwise Stress Model. Changes in locomotory behaviour were the most prominent in all species, thus the locomotion after 5 h (A5) was chosen as index for early warning responses. A new multimetric index (MI) for integrated biological and toxicological assessment of water affected by AMD is proposed: MI = (BMWP + ET + (100 - Predators(%) + A5) / 4.
Key words: acid mine drainage, integrated environmental monitoring, rapid bioassessment, online toxicity monitoring