Tracing the Origin and Evolution of Geochemical Characteristics of Waters from the Candiota Coal Mine Area (Southern Brazil): Part I
Autor: | Milton Luiz Laquintinie Formoso, M. Loubet, M. Munoz, Gilles Berger, Norberto Dani, Claudio Roisenberg |
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Rok vydání: | 2015 |
Předmět: |
Mineralogy
010501 environmental sciences engineering.material 010502 geochemistry & geophysics Geotechnical Engineering and Engineering Geology 01 natural sciences Salinity chemistry.chemical_compound chemistry Environmental chemistry engineering Carbonate Pyrite Sulfate Surface runoff Surface water Geology Groundwater 0105 earth and related environmental sciences Water Science and Technology Geochemical modeling |
Zdroj: | Mine Water and the Environment. 35:29-43 |
ISSN: | 1616-1068 1025-9112 |
Popis: | This work correlates surface and ground water composition to the substrata, and traces how water chemistry evolves at Brazil’s largest coal mine, the Candiota Mine. The water is dominated by SO4, Fe, Ca, and Mg. A pH range of 2.7–3 in the pit lakes is attributed through chemical models to concomitant pyrite oxidation and carbonate dissolution along with slow hydrolysis of aluminosilicate minerals and buffering provided by several iron oxy-hydroxide species. The Fe deficit of the surface water relative to the expected values is mainly due to precipitation of Fe sulfate salts, hydroxysulfates, and oxyhydroxides in the waste piles and their runoff. A progressive decrease in oxygen partial pressure with increased lake depth leads to destabilization of the iron oxyhydroxides/hydroxysulfates formed near the surface, which explains their absence from the lake sediment. Although interacting with similar rock types, the groundwater has a significantly different composition than the surface water, with less salinity and a pH of 5–6.5, due to limited oxygen and its evolution in a nearly closed system that stabilizes at higher pH values, which is controlled by carbonate/bicarbonate buffering. |
Databáze: | OpenAIRE |
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