Pb chronology and trace metal geochemistry at Los Tuxtlas, Mexico, as evidenced by a sedimentary record from the Lago Verde crater lake |
| |
Authors: | Ana Carolina Ruiz-Ferná ndez,Claude Hillaire-Marcel,Federico Pá ez-Osuna,Bassam Ghaleb,Margarita Caballero |
| |
Affiliation: | a Universidad Nacional Autónoma de México, Calz. J. Montes Camarena s/n., 82000 Mazatlán, Mexico b Centre de Recherche en Géochimie et en Géodynamique (GEOTOP-UQAM-McGill), 201 avenue du Président-Kennedy, Montréal, Qc, Canada H2X 3Y7 c Institute of Geophysics, UNAM, Circuito Ciudad Universitaria, 04510 México City, Mexico d El Colegio de Sinaloa, Rosales 435 Pte, Culiacán, Sin., Mexico |
| |
Abstract: | Lago Verde is a fresh-water maar found on the lower slopes of San Martin volcano, at the Sierra de Los Tuxtlas, Mexico, currently the northernmost remnant of the tropical rain forest in America. 210Pb and 137Cs analyzed in a sediment core were used to reconstruct the historical fluxes of Ag, Cd, Cu, Pb, Hg and Zn to the site during the last ∼ 150 yr. The 210Pbxs-derived sediment accumulation rates, the magnetic susceptibility, C/N ratios and δ13C data evidenced background conditions at the lake until 1960s, when enhanced erosion related to the clearing of large forested areas at Los Tuxtlas promoted higher accumulation rates of a heavier and more magnetic sedimentary material. Recent sediments from Lago Verde were found enriched by Pb (26-fold natural concentration level [NCLs]) and moderately enriched by Cd > Cu > Zn and Hg (6-, 5-, 4- and 4-fold corresponding NCLs, respectively). The fluxes of Cu, Hg, Pb and Zn have significantly increased since 1940s, with peak ratios of total modern to pre-industrial fluxes of 11, 11, 19 and 49, respectively. The lake occupies a relatively pristine, non-industrialized basin, and therefore the increased metal fluxes might be related to long-distance aeolian transport of trace metals. |
| |
Keywords: | 210Pb geochronology 137Cs Trace metal fluxes Maar Crater lake sediments Los Tuxtlas tropical rain forest |
本文献已被 ScienceDirect 等数据库收录! |
|