ABSTRACT
ABSTRACT: The distribution and fate of arsenic in various environmental reservoirs have been studied in Zimapán, México. Natural arsenic in groundwater is released by oxidation and dissolution of arsenic-bearing minerals. Mining wastes (tailings and smelter particulates) pollute some of the shallow wells. Tailings contain high concentration of As. However, As mobility is limited by oxidation-reduction, sorption, and formation of secondary minerals. Sequential extraction showed that As is mainly retained in the residual and Fe/Al oxyhydroxides fractions. Arsenic occurs also in beudantite and K-jarosite. High arsenic concentrations are found in soils and river sediments near tailings, slag piles and mineralized areas. Due to the semi-arid climate, few crops are grown in this area. Nevertheless, wild flora has grown on tailing and slag piles, and As-rich soils. Arsenic is absorbed from these As-rich substrates and translocated to the stem, leaves, flowers and fruits. The concentrations and fate of arsenic varies depending on the arsenic source.
