Title: Geochemistry, Bioavailability and Ecotoxicological Effects of Trace Metals Related To Iron Ore Mining - Case Study: Samarco Mineração, Brazil

Primary Researcher: Adriana Pereira
Email address: adriana.pereira@ivm.vu.nl
Submitted on: January 6, 2005

Start date: 01 September 2005
End date: 31 August 2009

Introduction:

The technologic and economic development of human society, based on high industrialization, requires an increase in metallic mineral supplies. However, these supplies require exploration of ore deposits and beneficiation of minerals, which frequently release different kinds of contaminants in soils, water and air. Mining and industrial wastes are environmental sources of heavy metals, also known as trace metals. Metal contamination of soils and waters is reported around the world and may have a severe impact of human health (Förstner, 1998), due to persistence and inherent toxicity of some trace metals.
Metal fate and bioavailability in water resources and tailings dams are dependent of some aspects of water quality. The presence of binding phases like organic matter, carbonates, sulfides and iron and manganese oxides may retain trace metals in the sediments and reduce the toxicity to aquatic organisms. On the other hand, solubilization of these phases under specific conditions may transfer trace metals into the dissolved fraction, which is considered to be the most mobile and most bioavailable form of trace metals (Salomons, 1998).
The distribution of trace metals in the different phases of the sediments determines their mobility, bioavailability and toxicity (Szefer et al., 1995). The knowledge of the physic-chemical forms in which trace metals exist in the sediments, rather than total quantification, is a tool to precisely locate the origin of metals (i.e., if they are related to anthropogenic sources or to background levels) and to understand their geochemical cycles and mobility. In spite of some limitations, sequential extraction techiniques are commonly used to study the speciation of sediment bound trace metals (Tessier et al., 1979; Tessier et al. 1985, Loring and Rantala, 1992, Quevaullier et al. 1997, Haese et al. 1997, Haese et al. 2000, Gómez-Ariza et al. 2000a, Gómez-Ariza et al. 2000b).
Some trace metals have the capacity to enter and remain in food webs for a long time (Szefer et al., 1998). Some species of organisms that accumulate and concentrate heavy metals in high levels can be used as biomonitors to reflect the extent of metal pollution and to assess their potential impacts in human health. Various species of mollusks and fish are commonly used as monitors.
Geochemical studies assessing the bioavailability of trace metals related to m

Aim:

This project aims at studying the environmental impacts from iron ore mining activities related to potential bioaccumulation of trace metals through the trophic chain and to toxicological effects in aquatic organisms. In this multidisciplinary study, involving geochemistry, environmental analytical chemistry and ecotoxicology, we will address the spatial distribution, geochemical speciation, bioavailability, bioaccumulation, trophic transfer and potential physiological effects of iron and associated trace metals. For the effect studies several potentially suitable and sensitive biomarkers will be tested and applied. The water resources influenced by the mining and pelletizing activities of Samarco Iron Ore in Brazil will be used as a case study in this research.

Research:

In summary the work will concentrate on exposure to and potential ecological risks of iron and trace elements in waters receiving effluents of iron ore mining (Doce river basin in Minas Gerais) and refining and pelleting operations in the coastal area at Ponta Ubu (Mãe-Bá lagoon, Espírito Santo). The assessment of exposure and bioavailability will be based on a characterization of the main biogeochemical processes governing the geochemical partitioning and fate of iron and trace metals in these systems and a description of the bioaccumulation in aquatic food webs. The metals that will be considered in the study, apart from the main constituents (Fe, Mn, etc.) are those commonly present in mining activities and recognized as potentially toxic at low concentrations to aquatic biota (e.g., Cd, Cu, Ni, Pb, Zn, Hg, Cr, Al and As). State-of-the-art testing methods will be used, like chemical methods (AAS, ICP-MS, ASV, AVS, sequential extractions, etc.) and methods for dating of segments of sediment cores. For the assessment of potential ecological risks, suitable biomarkers for potential physiological and biochemical effects of iron and trace metals will be tested and optimized in laboratory studies, and applied on suitable target organisms (fish, invertebrates) in the field studies. Laboratory bioassay experiments with Tilapia sp. (present in Mãe-Bá lagoon) are considered to evaluate the suitability of selected biomarkers or to corroborate findings form the field study. The experimental work in the field and sample preparation will be executed in close cooperation with the Centro de Biociências e Biotecnologia (CBB) of the Universidade Estadual do Norte Fluminense Darcy Ribeiro (UENF) in Campos dos Goytacazes (State of Rio de Janeiro). Specialized chemical analysis (ICP-MS), optimisation and screening with sensitive biomarkers for potential effects of iron and trace metals, and other laboratory studies will be executed at IVM in Amsterdam. It is expected that the study will provide important new information on the suitability of biomarkers as early-warning tools to study potential ecological effects in iron exposed environments and will contribute to a proper assessment of the local environmental risks.

External funding

Yes

External Funding Sponsors

CAPES - Ministry of Education - Brazil Samarco Mineração S/A