Effects of quarry mining and of other environmental impacts in the mountainous Chicam-Toctina drainage basin (Córdoba, Argentina) |
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| Authors: | D M Gaiero H E Pesci P J Depetris |
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| Institution: | (1) Cátedra de Química Analítica Mineral. Fac. de Cs. Ex. Fís. y Naturales. Universidad Nacional de Córdoba, Avda. Vélez Sársfield 299. 5000 Córdoba, Argentina, AR;(2) Municipalidad de Alta Gracia. Departamento de Sanidad Ambiental, Urquiza 358. 5186 Alta Gracia, Córdoba, Argentina, AR |
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| Abstract: | The environmental conditions prevailing in the Chicam-Toctina drainage system (approx. 138 km2 in Córdoba, Argentina) are considered representative of a number of catchments in Argentina's Sierras Pampeanas Range. Two
groups of ions reflect the sources of dissolved species in the catchment: a) a group (Cl–, SO2–
4, and Na+) which recognizes natural and anthropogenic sources, and which exhibits significant correlations with N–
3 and NO–
2, and b) another group of components (Ca2+, Mg2+, and HCO–
3) which is clearly controlled by carbonate rocks and their waste rock products. In the headwaters, stockpiled marble quarry
mining wastes provide a more open system to CO2 gaseous exchange than the outcropping rocks, thus promoting the increase of carbonate dissolution (up to 4.88 g km–2 s–1 during the rainy season). This specific yield was 20% higher than the amount estimated for an area with fewer extended mining
activities. The dissolved load delivered by the upper reaches is subjected in the lower drainage area to various processes,
mainly controlled by the presence of the city of Alta Gracia (approx. 40,000 inhabitants). In the dry season, due to nutrient
inputs supplied by the city, photosynthetic activity plays a major role controlling stream pH. Hence, the high values of calcite
saturation indexes and the increase of CaCO3 concentration in bed sediments can be explained by calcite precipitation. Such a process could be accompanied by the coprecipitation
on calcium carbonate of low solubility heavy metal carbonates.
Received : 17 January 1997 · Accepted : 31 March 1997 |
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| Keywords: | Quarry mining Waste rocks Marble Domestic pollution |
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