ORIGINAL ARTICLE Geochemical distribution of arsenic, cadmium, lead and zinc in river sediments affected by tailings in Zimapa ´n, a historical polymetalic mining zone of Me ´xico Erik Espinosa Æ Marı ´a Aurora Armienta Æ Olivia Cruz Æ Alejandra Aguayo Æ Nora Ceniceros Received: 12 August 2008 / Revised: 17 October 2008 / Accepted: 14 November 2008 / Published online: 6 January 2009 Ó Springer-Verlag 2008 Abstract In the historical mining zone of Zimapa ´n, Me ´xico, unprotected tailings deposits are supplying con- taminants to the local fluvial system. This research was conducted to assess the environmental hazard of these wastes and river sediments by determining the input, transport and seasonal variability of arsenic, cadmium, lead and zinc, and their speciation by an operationally defined scheme of decreasing lability: F1, fraction soluble in deionized water; F2, associated to carbonates; F3, oxides and hydroxides of iron; F4, sulfides and organic matter; F5, residual. Higher total concentrations of Cd, Pb and Zn were present in sediments in the dry season regarding the rainy season. In the dry season, As and Pb were principally associated with the more stable F3 and F5 fractions, whereas Cd was in F2 and F5, and Zn in F3, F2 and F5. In the rainy season the association was mainly F3 for As, while F2 and F3 contained most Cd, Pb and Zn. This fractionation indicates that the environmental hazard of Cd, Pb and Zn enhances upon a pH decrease due to their pro- portion in the carbonatic fraction, and shows a mobility increase during the rainy season. Keywords Arsenic  Heavy metals  Mexico  Sediments  Speciation  Mining Introduction Since the seventeenth century the obtention of lead, silver and zinc has been an important economic activity in the mining district of Zimapa ´n, Hidalgo State, Me ´xico, located at 200 km north of Me ´xico City (20°44.12 0 N latitude, 99°23.50 0 W longitude, and 1,780 m above sea level). At the beginning of this activity the ore was processed by smelting in the town until 1939, when it was transported to San Luis Potosı ´ State. Afterwards, since the middle of the twentieth century, the ore has been processed in Zimapa ´n by selective flotation in various facilities. The generated tailings were transported and deposited in the vicinity of Zimapa ´n town close to the riverbed of the Tolima ´n River. The oldest red tailings (RT), deposited about 60 years ago (described by Me ´ndez and Armienta 2003) are oxidized and generate leachates, that flow directly to the river. The recent mine wastes called San Miguel Nuevo (SMN) and San Miguel Viejo (SMV) have not undergone extensive oxidation yet. However, because these deposits do not have a protective cover, the tailing particulates have been dis- persed by different means (windblow and gravity) to the surroundings. As a result of these processes the river sys- tem has received this contaminant load (arsenic and heavy metals as cadmium, lead and zinc) which is delivered into the aqueous and mainly to the solid phases (sediments). Armienta et al. (2007) have considered these materials as an antropogenic source of arsenic to the groundwater of Zimapa ´n valley. Zimapa ´n has a semi-arid climate with summer rains and an average annual precipitation of 631 ± 14 mm for the period of 2000–2004 (SMN 2008). Based on these climatic characteristics, two sampling campaigns (during the dry and rainy seasons) were carried out in 2005. However, in 2005 two hurricanes: the tropical storm ‘‘Jose ´’’ (22–23 of E. Espinosa  M. A. Armienta (&)  O. Cruz  A. Aguayo  N. Ceniceros Instituto de Geofı ´sica, Universidad Nacional Auto ´noma de Me ´xico (UNAM), Circuito Exterior, CU, 04510 Me ´xico, DF, Mexico e-mail: victoria@geofisica.unam.mx 123 Environ Geol (2009) 58:1467–1477 DOI 10.1007/s00254-008-1649-6