Trace elements in a tropical coastal lagoon in Brazil receiving effluents from iron-ore mining and processing

Integrated field studies on environmental levels, bioavailability, biological exposure, and effects SUMMARY Iron-ore is the source of primary iron for the world's iron and steel industries. Almost all (98%) iron-ore is used in steelmaking. Australia and Brazil together dominate the world's iron-ore production, while China is the world's largest iron-ore consumer. In Brazil, iron-ore mining is mainly located in the southeast. The area is also scattered with gold occurrence. In the past, artisanal small scale gold mining activities were frequent in this area. This study deals with activities of the iron-ore mining, concentration plant, and pelletizing plant operated by Samarco Mineração S/A. A pipeline (396 km long), transports the ore from the mining and concentration site (mixed with water) to the pelletizing plant at the coast. In this plant, the ore is separated from the water and the effluent goes to an artificial lake (North Dam). Periodically, this artificial lake overflows into Mãe-Bá coastal lagoon. The main objective of the work presented in this thesis was to investigate possible impacts of iron-ore mining and processing activities on local environmental levels of trace elements and possible consequences thereof for fish species of Mãe-Bá Lagoon, using a multidisciplinary approach. For comparisons we selected similar lagoons in the vicinity and not directly influenced by the iron-ore processing activities. Based on a series of field studies, the possible influence of iron-ore mining and processing activities on the release of metals bioavailability was examined in different aquatic systems (rivers and coastal lagoons) (Chapter two). Furthermore, trace element levels were measured in invertebrates and fish to assess potential trace element bioaccumulation and trophic transfer, as well as potential risks to human health due to consumption of fish (Chapters two and three). Moreover, possible changes in biochemical markers of exposure and effects of trace elements were investigated in fish species from the coastal lagoons (Chapters four and five). The main findings of the studies presented in this thesis are: