Mercury, zinc, manganese, and iron accumulation in leachate pondsediments from a refuse tip in Southeastern Brazil

Abstract

This work evaluates Hg, Zn, Fe and Mn transfer from the leachate of a refuse tip based on their accumulation in a sediment core of 17 cmcollected in a leachate pond of a small refuse tip ageing approximately 10 years. Sediment samples were digested with an acid mixture (50%acqua regiasolution), heated at 70 °C during 1 h, in a thermal-kinetic reactor“cold finger”. The extract was analysed to obtain Hg content by coldvapour absorption atomic spectrometry (CVAAS). Fe, Mn and Zn contents were obtained by flame atomic absorption spectrometry (FAAS) aftertotal decomposition of the samples. Concentration ranges along the core varied from 0.16 to 0.58μgg−1; 7.3 to 145μgg−1; 11.7 to 116μgg−1and 0.21% to 1.82% for Hg, Zn, Mn and Fe, respectively. All metals showed enrichment in the upper layers (above 6 cm) which probablycorrespond to the year 1996. Results indicated that Hg transfer is one order of magnitude higher than Zn and suggest that metals accumulation insediments probably reduce their migration to groundwater.© 2006 Elsevier B.V. All rights reserved.