Mercury, zinc, and copper accumulation in mangrove sediments surrounding a large landfill in southeast Brazil

Abstract

The accumulation of Hg, Zn, and Cu was evaluated in mangrove sediments located between a large, 20-years-old landfill and waters of Guanabara Bay (southeast Brazil). The contamination history of the area provides substantial evidence that metal accu- mulation in the study site is influenced by past metal emissions from multiple sources (e.g. contaminated rivers and the landfill surrounding the site). At the southern part of the site, metal levels are up to 890 ng g 1 Hg, 850 mg g 1 Zn, and 58 mg g 1 Cu. Enrichment factors and excess (background-deducted) concentration inventories show a high spatial variability of metal con- tamination and storage in the site, with differences often by a factor higher than two within a sampling station and higher than five between sampling stations. These contrasts are attributable to a coupling between spatial variability of anthropogenic metal input and metal behavior and retention within the sediments. Results indicate that during the last few decades mangrove sediments retained a substantial part of metal emissions to the site, probably reducing the metal transport to Guanabara Bay waters, and suggest the suitability of mangrove ecosystems as physical and biogeochemical barriers to metal contaminant transport. # 2002 Elsevier Science Ltd. All rights reserved