Characterization of Hydrological and Hydrochemical Cycles as a Tool for Evaluation of Environmental Impact of Mining in Serra Dos Carajas, Amazonia, Brazil
| Autor: | I. Weissberg |
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| Rok vydání: | 1991 |
| Předmět: | |
| Zdroj: | Water Science and Technology. 24:117-126 |
| ISSN: | 1996-9732 0273-1223 |
| DOI: | 10.2166/wst.1991.0344 |
| Popis: | The objective of this work is to show the importance of knowing, in detail, the hydrological and hydrochemical cycles so as to define the dynamic conditions for an ecosystem equilibrium and to detect the modifications introduced by open-cast mining, which is a potential cause of environmental impact. Over four years research was carried out in the Carajas area to evaluate the elimate, soil and water characteristics. About the five hundred and fifty water samples from rivers, lakes and “igarapé” were collected and analysed from forty different points of the area. At nine different points, two hundred sixteen soil samples were collected and analysed. The analysed results were assembled with pluviometry, humidity, potential evaporation, insolation and temperature data for the area. The data reveal that residence time of water is short in all “stages” of the cycles (convective rain); the pH is acidic (between 4.5 and 6.0) with high values of free CO2 (average 30 ppm) and saturated in dissolved O2 (average 8.O ppm) which produces a high degree of water reactivity when in contact with the surface. The Carajas ecosystem is in dynamic equilibrium with these conditions. The water percolation through tailings from iron and manganese mining produces an agent that dissolves and removes mineral particles that in run off arrives in surface and groundwater, changing its physical-chemical equilibrium and disturbs the aquatic biota. At the start of exploration were detected Cr 0.14 ppm, Mn 0.43ppm, Pb 0.20 ppm and Ni 0.04ppm. Salobo polymetals deposit has a very complex mineral paragenesis with Cu, pb, Ag, Mo, Co, Zn and other metals such as sulfide. This deposit has a high pollution potential since its tailings will will be exposed in the open. |
| Databáze: | OpenAIRE |
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