Benthic methylmercury production in lacustrine ecosystems of Nahuel Huapi National Park, Patagonia, Argentina

• Published in: Chemosphere (Oxford) 2009-10, Vol.77 (4), p.471-477
• Main Authors: Ribeiro Guevara, Sergio, Catán, Soledad Pérez, Marvin-DiPasquale, Mark
• Format: Article
• Language: English
• Subjects: 197Hg mercury tracer; Air. Soil. Water. Waste. Feeding; Animal, plant and microbial ecology; Applied ecology; Applied sciences; Argentina; Biological and medical sciences; Dissolved organic matter; Ecosystem; Ecosystems; Ecotoxicology, biological effects of pollution; Environment. Living conditions; Environmental Monitoring; Exact sciences and technology; Freshwater; Fundamental and applied biological sciences. Psychology; Geologic Sediments - chemistry; Lake sediment; Lakes; Littoral environments; Medical sciences; Mercury; Mercury - analysis; Mercury methylation; Mercury Radioisotopes - chemistry; Methylmercury Compounds - analysis; Methylmercury Compounds - chemistry; Microorganisms; Nahuel Huapi National Park; Pollution; Public health. Hygiene; Public health. Hygiene-occupational medicine; Seasonal variations; Seasons; Sediments; Soil Pollutants - analysis; Soil Pollutants - chemistry
• ISSN: 0045-6535; 1879-1298
• DOI: 10.1016/j.chemosphere.2009.07.055

Seasonal trends of benthic methylmercury (methyl-Hg) production were examined in both littoral and open water sites of three lakes (Escondido, Moreno, and Morenito) in the North Andean Patagonia region of Argentina. Potentials of methyl-Hg production were measured by amending sediment samples with inorganic 197Hg(II), incubating for either 24 and 32 h at room temperature, and subsequently assaying the radiolabelled organomercury produced. Seasonal variations of benthic methyl-Hg production were studied but no significant correlation was observed. Lake littoral sites exhibited up to two fold higher methyl-Hg production potentials in most cases. Sediment from lakes Moreno and Morenito generally exhibited much lower (up to 10 fold) methyl-Hg production potentials than those from Lake Escondido, possibly due to differences in particulate and dissolved organic matter quantity and quality, which is higher in Lake Escondido and primarily allochthonous, whereas in lakes Moreno and Morenito is primarily autochthonous. This study represents the first to directly examine benthic microbial Hg(II)-methylation in aquatic ecosystems of Patagonia.