200 years of mining activities at La Paz/San Luis Potosí/Mexico - Consequences for environment and geochemical exploration |
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| Authors: | Javier Castro-Larragoitia Utz Kramar Harald Puchelt |
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| Institution: | aFacultad de Ciencias de La Tierra, U.A.N.L, A.P. 104, 67000 Linares, N.L., Mexico;bInstitute of Petrography and Geochemistry, Unirersity of Karlsruhe. Kaiserstr. 12, D-76128 Karlsruhe, Germany |
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| Abstract: | The Ag---Pb---Zn---Cu---Au mining district of Santa María de La Paz has been extensively exploited for approximately 200 years. Consequences of these activities are several deposits of tailings with high As and heavy metal concentrations, which are completely unstable. The climate is semiarid and as the dumps have no protective cover, material from the dumps is dispersed by strong winds. It is also washed out during seasonally heavy rainfalls. By these processes approximately 100 km2 of surrounding have been contaminated by dump material. The As and heavy metal content of the soils was determined as well as their level in crops (Zea Maize) from agricultural lands in the vicinity of the dumps. In the direction of prevailing winds concentrations up to 1000 ppm Zn, 400 ppm Pb, 16 ppm Cd, 550 ppm Cu and 300 As have been detected in top soils. Using fuzzy cluster analysis the different contamination sources could be identified. Grains of corn from contaminated sites showed no critical concentrations, but leaves which are also used tor fodder, have As-concentrations up to 20 ppm. |
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| Keywords: | environment soil heavy metals arsenic mine tailings Mexico |
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