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(M/MF161) Are community parameters a suitable tool to assess risks in a contaminated mining area? Pereira, Ruth1, Pestana, João1, Abrantes, Nelson1, Ribeiro, Rui2, Gonçalves, Fernando1, 1 2 ABSTRACT- Chemical distribution in natural soils is highly discontinuous and contamination is rarely attributed to a single chemical. This comes as a difficulty in assessing the direct and indirect effects yield by contamination by heavy metals, mimicking natural conditions to laboratory. As far as soil invertebrates are concerned, due to their ecological and economic significance, they have to be taken under careful consideration when potential risks posed by contamination by heavy metals in natural soils are to be determined. The main purpose of this study, incorporated in the environmental risk assessment that is being performed in an abandoned mine area, was to assess effects at invertebrate community level. The end-points were total abundances and diversity indexes. After soil characterisation 105 pitfall traps were positioned in different areas (EU - environmental units) at different distances from the mine. Different vegetation patches were considered within each area. Collembola and Formicidae were the main abundant groups. Significant differences in abundances were found between vegetation patches in some environmental units. No differences were found between abundances and diversity indexes at different EU. Those results could be explained by the development of tolerance mechanisms by invertebrates since numerous studies have demonstrated that population densities and/or species number decrease significantly in the direction of a metal contaminated place. To confirm this suspicion and once the general characterisation of the community was already made, this study should proceed in order to develop toxicity tests, to assess soil toxicity to a specific species (e.g., Collembola). Key words: mine soils, heavy metals, soil invertebrates, community levels effects |
